Merge branch 'inline-server'
This commit is contained in:
Mark McGranaghan
commit
eadc7bb348
60
README.md
60
README.md
@ -1,6 +1,6 @@
|
||||
## Go by Example
|
||||
|
||||
Content and toolchain for [Go by Example](https://gobyexample.com).
|
||||
Content, toolchain, and web server for [Go by Example](https://gobyexample.com).
|
||||
|
||||
|
||||
### Overview
|
||||
@ -10,10 +10,9 @@ comments from source files in `examples` and rendering
|
||||
that data via the site `templates`. The programs
|
||||
implementing this build process are in `tools`.
|
||||
|
||||
The build process produces a directory of static files
|
||||
suitable for serving by any modern HTTP server. The
|
||||
Go by Example site is served by a
|
||||
[lightweight Go server](https://github.com/mmcgrana/gobyexample-server).
|
||||
The build process produces a directory of static files -
|
||||
`public` - suitable for serving by any modern HTTP server.
|
||||
We include a lightweight Go server in `server.go`.
|
||||
|
||||
|
||||
### Building
|
||||
@ -22,7 +21,7 @@ To build the site:
|
||||
|
||||
```console
|
||||
$ tools/build
|
||||
$ open site/index.html
|
||||
$ open public/index.html
|
||||
```
|
||||
|
||||
To build continuously in a loop:
|
||||
@ -40,16 +39,53 @@ $ export PATH="$HOME/repos/pygments:$PATH"
|
||||
```
|
||||
|
||||
|
||||
### Serving
|
||||
### Local Deploy
|
||||
|
||||
The site is served by the [gobyexample-server](https://github.com/mmcgrana/gobyexample-server)
|
||||
tool. To export to this tool:
|
||||
|
||||
```console
|
||||
$ SITEDIR=../gobyexample-server/public tool/build
|
||||
```bash
|
||||
$ mkdir -p $GOPATH/src/github.com/mmcgrana
|
||||
$ cd $GOPATH/src/github.com/mmcgrana
|
||||
$ git clone git@github.com:mmcgrana/gobyexaple.git
|
||||
$ cd gobyexample
|
||||
$ go get
|
||||
$ foreman start
|
||||
$ foreman open
|
||||
```
|
||||
|
||||
|
||||
### Platform Deploy
|
||||
|
||||
Basic setup:
|
||||
|
||||
```bash
|
||||
$ export DEPLOY=$USER
|
||||
$ heroku create gobyexample-$DEPLOY -r $DEPLOY
|
||||
$ heroku config:add -r $DEPLOY \
|
||||
BUILDPACK_URL=https://github.com/kr/heroku-buildpack-go.git -r $DEPLOY \
|
||||
CANONICAL_HOST=gobyexample-$DEPLOY.herokuapp.com -r $DEPLOY \
|
||||
FORCE_HTTPS=1 \
|
||||
AUTH=go:byexample
|
||||
$ git push $DEPLOY master
|
||||
$ heroku open -r $DEPLOY
|
||||
```
|
||||
|
||||
Add a domain + SSL:
|
||||
|
||||
```bash
|
||||
$ heroku domains:add $DOMAIN
|
||||
$ heroku addons:add ssl -r $DEPLOY
|
||||
# order ssl cert for domain
|
||||
$ cat > /tmp/server.key
|
||||
$ cat > /tmp/server.crt.orig
|
||||
$ cat /tmp/server.crt.orig /tmp/rapidssl_bundle.pem > /tmp/server.crt
|
||||
$ heroku certs:add /tmp/server.crt /tmp/server.key -r $DEPLOY
|
||||
# add ALIAS record from domain to ssl endpoint dns
|
||||
$ heroku config:add CANONICAL_HOST=$DOMAIN -r $DEPLOY
|
||||
$ heroku open -r $DEPLOY
|
||||
```
|
||||
|
||||
|
||||
|
||||
|
||||
### License
|
||||
|
||||
This work is licensed under a
|
||||
|
||||
29
public/404.html
Normal file
29
public/404.html
Normal file
@ -0,0 +1,29 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Not Found</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div id="intro">
|
||||
<h2><a href="./">Go by Example</a></h2>
|
||||
<p>Sorry, we couldn't find that! Check out the <a href="./">home page</a>?</p>
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
195
public/arrays
Normal file
195
public/arrays
Normal file
@ -0,0 +1,195 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Arrays</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="arrays">
|
||||
<h2><a href="./">Go by Example</a>: Arrays</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>In Go, an <em>array</em> is a numbered sequence of elements of a
|
||||
specific length.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Here we create an array <code>a</code> that will hold exactly
|
||||
5 <code>int</code>s. The type of elements and length are both
|
||||
part of the array’s type. By default an array is
|
||||
zero-valued, which for <code>int</code>s means <code>0</code>s.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="kd">var</span> <span class="nx">a</span> <span class="p">[</span><span class="mi">5</span><span class="p">]</span><span class="kt">int</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"emp:"</span><span class="p">,</span> <span class="nx">a</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>We can set a value at an index using the
|
||||
<code>array[index] = value</code> syntax, and get a value with
|
||||
<code>array[index]</code>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">a</span><span class="p">[</span><span class="mi">4</span><span class="p">]</span> <span class="p">=</span> <span class="mi">100</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"set:"</span><span class="p">,</span> <span class="nx">a</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"get:"</span><span class="p">,</span> <span class="nx">a</span><span class="p">[</span><span class="mi">4</span><span class="p">])</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>The builtin <code>len</code> returns the length of an array.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"len:"</span><span class="p">,</span> <span class="nb">len</span><span class="p">(</span><span class="nx">a</span><span class="p">))</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Use this syntax to declare and initalize an array
|
||||
in one line.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">b</span> <span class="o">:=</span> <span class="p">[</span><span class="mi">5</span><span class="p">]</span><span class="kt">int</span><span class="p">{</span><span class="mi">1</span><span class="p">,</span> <span class="mi">2</span><span class="p">,</span> <span class="mi">3</span><span class="p">,</span> <span class="mi">4</span><span class="p">,</span> <span class="mi">5</span><span class="p">}</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"dcl:"</span><span class="p">,</span> <span class="nx">b</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Array types are one-dimensional, but you can
|
||||
compose types to build multi-dimensional data
|
||||
structures.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre> <span class="kd">var</span> <span class="nx">twoD</span> <span class="p">[</span><span class="mi">2</span><span class="p">][</span><span class="mi">3</span><span class="p">]</span><span class="kt">int</span>
|
||||
<span class="k">for</span> <span class="nx">i</span> <span class="o">:=</span> <span class="mi">0</span><span class="p">;</span> <span class="nx">i</span> <span class="p"><</span> <span class="mi">2</span><span class="p">;</span> <span class="nx">i</span><span class="o">++</span> <span class="p">{</span>
|
||||
<span class="k">for</span> <span class="nx">j</span> <span class="o">:=</span> <span class="mi">0</span><span class="p">;</span> <span class="nx">j</span> <span class="p"><</span> <span class="mi">3</span><span class="p">;</span> <span class="nx">j</span><span class="o">++</span> <span class="p">{</span>
|
||||
<span class="nx">twoD</span><span class="p">[</span><span class="nx">i</span><span class="p">][</span><span class="nx">j</span><span class="p">]</span> <span class="p">=</span> <span class="nx">i</span> <span class="o">+</span> <span class="nx">j</span>
|
||||
<span class="p">}</span>
|
||||
<span class="p">}</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"2d: "</span><span class="p">,</span> <span class="nx">twoD</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Note that arrays appear in the form <code>[v1 v2 v3 ...]</code>
|
||||
when printed with <code>fmt.Println</code>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run arrays.go
|
||||
<span class="go">emp: [0 0 0 0 0]</span>
|
||||
<span class="go">set: [0 0 0 0 100]</span>
|
||||
<span class="go">get: 100</span>
|
||||
<span class="go">len: 5</span>
|
||||
<span class="go">dcl: [1 2 3 4 5]</span>
|
||||
<span class="go">2d: [[0 1 2] [1 2 3]]</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>You’ll see <em>slices</em> much more often than arrays in
|
||||
typical Go. We’ll look at slices next.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="slices">Slices</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/arrays">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
207
public/atomic-counters
Normal file
207
public/atomic-counters
Normal file
@ -0,0 +1,207 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Atomic Counters</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="atomic-counters">
|
||||
<h2><a href="./">Go by Example</a>: Atomic Counters</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>The primary mechanism for managing state in Go is
|
||||
communication over channels. We saw this for example
|
||||
with <a href="worker-pool">worker pools</a>. There are a few other
|
||||
options for managing state though. Here we’ll
|
||||
look at using the <code>sync/atomic</code> package for <em>atomic
|
||||
counters</em> accessed by multiple goroutines.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
<span class="kn">import</span> <span class="s">"time"</span>
|
||||
<span class="kn">import</span> <span class="s">"sync/atomic"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>We’ll use an unsigned integer to represent our
|
||||
(always-positive) counter.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="kd">var</span> <span class="nx">ops</span> <span class="kt">uint64</span> <span class="p">=</span> <span class="mi">0</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>To simulate concurrent updates, we’ll start 50
|
||||
goroutines that each increment the counter about
|
||||
once a millisecond.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="k">for</span> <span class="nx">i</span> <span class="o">:=</span> <span class="mi">0</span><span class="p">;</span> <span class="nx">i</span> <span class="p"><</span> <span class="mi">50</span><span class="p">;</span> <span class="nx">i</span><span class="o">++</span> <span class="p">{</span>
|
||||
<span class="k">go</span> <span class="kd">func</span><span class="p">()</span> <span class="p">{</span>
|
||||
<span class="k">for</span> <span class="p">{</span>
|
||||
<span class="nx">time</span><span class="p">.</span><span class="nx">Sleep</span><span class="p">(</span><span class="nx">time</span><span class="p">.</span><span class="nx">Millisecond</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>To atomically increment the counter we
|
||||
use <code>AddUint64</code>, giving it the memory
|
||||
address of our <code>ops</code> counter with the
|
||||
<code>&</code> syntax.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">atomic</span><span class="p">.</span><span class="nx">AddUint64</span><span class="p">(</span><span class="o">&</span><span class="nx">ops</span><span class="p">,</span> <span class="mi">1</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
<span class="p">}()</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Wait a second to allow some ops to accumulate.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">time</span><span class="p">.</span><span class="nx">Sleep</span><span class="p">(</span><span class="nx">time</span><span class="p">.</span><span class="nx">Second</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>In order to safely use the counter while it’s still
|
||||
being updated by other goroutines, we extract a
|
||||
copy of the current value into <code>opsFinal</code> via
|
||||
<code>LoadUint64</code>. As above we need to give this
|
||||
function the memory address <code>&ops</code> from which to
|
||||
fetch the value.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">opsFinal</span> <span class="o">:=</span> <span class="nx">atomic</span><span class="p">.</span><span class="nx">LoadUint64</span><span class="p">(</span><span class="o">&</span><span class="nx">ops</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"ops:"</span><span class="p">,</span> <span class="nx">opsFinal</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Next we’ll look at another approach to managing state:
|
||||
mutexes.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Running the program shows that we executed about
|
||||
40,000 operations.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run atomic-counters.go
|
||||
<span class="go">ops: 40200</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Next we’ll look at mutexes, another tool for managing
|
||||
state.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="mutexes">Mutexes</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/atomic-counters">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
179
public/base64-encoding
Normal file
179
public/base64-encoding
Normal file
@ -0,0 +1,179 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Base64 Encoding</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="base64-encoding">
|
||||
<h2><a href="./">Go by Example</a>: Base64 Encoding</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Go provides built-in support for <a href="http://en.wikipedia.org/wiki/Base64">base64
|
||||
encoding/decoding</a>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>This syntax imports the <code>encoding/base64</code> package with
|
||||
the <code>b64</code> name instead of the default <code>base64</code>. It’ll
|
||||
save us some space below.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="nx">b64</span> <span class="s">"encoding/base64"</span>
|
||||
<span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Here’s the <code>string</code> we’ll encode/decode.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">data</span> <span class="o">:=</span> <span class="s">"abc123!?$*&()'-=@~"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Go supports both standard and URL-compatible
|
||||
base64. Here’s how to encode using the standard
|
||||
encoder. The encoder requires a <code>[]byte</code> so we
|
||||
cast our <code>string</code> to that type.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">sEnc</span> <span class="o">:=</span> <span class="nx">b64</span><span class="p">.</span><span class="nx">StdEncoding</span><span class="p">.</span><span class="nx">EncodeToString</span><span class="p">([]</span><span class="nb">byte</span><span class="p">(</span><span class="nx">data</span><span class="p">))</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">sEnc</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Decoding may return an error, which you can check
|
||||
if you don’t already know the input to be
|
||||
well-formed.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">sDec</span><span class="p">,</span> <span class="nx">_</span> <span class="o">:=</span> <span class="nx">b64</span><span class="p">.</span><span class="nx">StdEncoding</span><span class="p">.</span><span class="nx">DecodeString</span><span class="p">(</span><span class="nx">sEnc</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nb">string</span><span class="p">(</span><span class="nx">sDec</span><span class="p">))</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">()</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>This encodes/decodes using a URL-compatible base64
|
||||
format.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre> <span class="nx">uEnc</span> <span class="o">:=</span> <span class="nx">b64</span><span class="p">.</span><span class="nx">URLEncoding</span><span class="p">.</span><span class="nx">EncodeToString</span><span class="p">([]</span><span class="nb">byte</span><span class="p">(</span><span class="nx">data</span><span class="p">))</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">uEnc</span><span class="p">)</span>
|
||||
<span class="nx">uDec</span><span class="p">,</span> <span class="nx">_</span> <span class="o">:=</span> <span class="nx">b64</span><span class="p">.</span><span class="nx">URLEncoding</span><span class="p">.</span><span class="nx">DecodeString</span><span class="p">(</span><span class="nx">uEnc</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nb">string</span><span class="p">(</span><span class="nx">uDec</span><span class="p">))</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>The string encodes to slightly different values with the
|
||||
standard and URL base64 encoders (trailing <code>+</code> vs <code>-</code>)
|
||||
but they both decode to the original string as desired.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run base64-encoding.sh
|
||||
<span class="go">YWJjMTIzIT8kKiYoKSctPUB+</span>
|
||||
<span class="go">abc123!?$*&()'-=@~</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre><span class="go">YWJjMTIzIT8kKiYoKSctPUB-</span>
|
||||
<span class="go">abc123!?$*&()'-=@~</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="reading-files">Reading Files</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/base64-encoding">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
145
public/channel-buffering
Normal file
145
public/channel-buffering
Normal file
@ -0,0 +1,145 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Channel Buffering</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="channel-buffering">
|
||||
<h2><a href="./">Go by Example</a>: Channel Buffering</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>By default channels are <em>unbuffered</em>, meaning that they
|
||||
will only accept sends (<code>chan <-</code>) if there is a
|
||||
corresponding receive (<code><- chan</code>) ready to receive the
|
||||
sent value. <em>Buffered channels</em> accept a limited
|
||||
number of values without a corresponding receiver for
|
||||
those values.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Here we <code>make</code> a channel of strings buffering up to
|
||||
2 values.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">messages</span> <span class="o">:=</span> <span class="nb">make</span><span class="p">(</span><span class="kd">chan</span> <span class="kt">string</span><span class="p">,</span> <span class="mi">2</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Because this channel is buffered, we can send these
|
||||
values into the channel without a corresponding
|
||||
concurrent receive.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">messages</span> <span class="o"><-</span> <span class="s">"buffered"</span>
|
||||
<span class="nx">messages</span> <span class="o"><-</span> <span class="s">"channel"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Later we can receive these two values as usual.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="o"><-</span><span class="nx">messages</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="o"><-</span><span class="nx">messages</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run channel-buffering.go
|
||||
<span class="go">buffered</span>
|
||||
<span class="go">channel</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="channel-synchronization">Channel Synchronization</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/channel-buffering">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
138
public/channel-directions
Normal file
138
public/channel-directions
Normal file
@ -0,0 +1,138 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Channel Directions</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="channel-directions">
|
||||
<h2><a href="./">Go by Example</a>: Channel Directions</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>When using channels as function parameters, you can
|
||||
specify if a channel is meant to only send or receive
|
||||
values. This specificity increases the type-safety of
|
||||
the program.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>This <code>ping</code> function only accepts a channel for sending
|
||||
values. It would be a compile-time error to try to
|
||||
receive on this channel.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">ping</span><span class="p">(</span><span class="nx">pings</span> <span class="kd">chan</span><span class="o"><-</span> <span class="kt">string</span><span class="p">,</span> <span class="nx">msg</span> <span class="kt">string</span><span class="p">)</span> <span class="p">{</span>
|
||||
<span class="nx">pings</span> <span class="o"><-</span> <span class="nx">msg</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>The <code>pong</code> function accepts one channel for receives
|
||||
(<code>pings</code>) and a second for sends (<code>pongs</code>).</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">pong</span><span class="p">(</span><span class="nx">pings</span> <span class="o"><-</span><span class="kd">chan</span> <span class="kt">string</span><span class="p">,</span> <span class="nx">pongs</span> <span class="kd">chan</span><span class="o"><-</span> <span class="kt">string</span><span class="p">)</span> <span class="p">{</span>
|
||||
<span class="nx">msg</span> <span class="o">:=</span> <span class="o"><-</span><span class="nx">pings</span>
|
||||
<span class="nx">pongs</span> <span class="o"><-</span> <span class="nx">msg</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
<span class="nx">pings</span> <span class="o">:=</span> <span class="nb">make</span><span class="p">(</span><span class="kd">chan</span> <span class="kt">string</span><span class="p">,</span> <span class="mi">1</span><span class="p">)</span>
|
||||
<span class="nx">pongs</span> <span class="o">:=</span> <span class="nb">make</span><span class="p">(</span><span class="kd">chan</span> <span class="kt">string</span><span class="p">,</span> <span class="mi">1</span><span class="p">)</span>
|
||||
<span class="nx">ping</span><span class="p">(</span><span class="nx">pings</span><span class="p">,</span> <span class="s">"passed message"</span><span class="p">)</span>
|
||||
<span class="nx">pong</span><span class="p">(</span><span class="nx">pings</span><span class="p">,</span> <span class="nx">pongs</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="o"><-</span><span class="nx">pongs</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run channel-directions.go
|
||||
<span class="go">passed message</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="select">Select</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/channel-directions">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
170
public/channel-synchronization
Normal file
170
public/channel-synchronization
Normal file
@ -0,0 +1,170 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Channel Synchronization</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="channel-synchronization">
|
||||
<h2><a href="./">Go by Example</a>: Channel Synchronization</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>We can use channels to synchronize execution
|
||||
across goroutines. Here’s an example of using a
|
||||
blocking receive to wait for a goroutine to finish.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
<span class="kn">import</span> <span class="s">"time"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>This is the function we’ll run in a goroutine. The
|
||||
<code>done</code> channel will be used to notify another
|
||||
goroutine that this function’s work is done.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">worker</span><span class="p">(</span><span class="nx">done</span> <span class="kd">chan</span> <span class="kt">bool</span><span class="p">)</span> <span class="p">{</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Print</span><span class="p">(</span><span class="s">"working..."</span><span class="p">)</span>
|
||||
<span class="nx">time</span><span class="p">.</span><span class="nx">Sleep</span><span class="p">(</span><span class="nx">time</span><span class="p">.</span><span class="nx">Second</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"done"</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Send a value to notify that we’re done.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">done</span> <span class="o"><-</span> <span class="kc">true</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Start a worker goroutine, giving it the channel to
|
||||
notify on.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">done</span> <span class="o">:=</span> <span class="nb">make</span><span class="p">(</span><span class="kd">chan</span> <span class="kt">bool</span><span class="p">,</span> <span class="mi">1</span><span class="p">)</span>
|
||||
<span class="k">go</span> <span class="nx">worker</span><span class="p">(</span><span class="nx">done</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Block until we receive a notification from the
|
||||
worker on the channel.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre> <span class="o"><-</span><span class="nx">done</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run channel-synchronization.go
|
||||
<span class="go">working...done </span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>If you removed the <code><- done</code> line from this program, the
|
||||
program would exit before the <code>worker</code> even
|
||||
started.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="channel-directions">Channel Directions</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/channel-synchronization">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
160
public/channels
Normal file
160
public/channels
Normal file
@ -0,0 +1,160 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Channels</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="channels">
|
||||
<h2><a href="./">Go by Example</a>: Channels</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p><em>Channels</em> are the pipes that connect concurrent
|
||||
goroutines. You can send values into channels from one
|
||||
goroutine and receive those values into another
|
||||
goroutine. Channels are a powerful primitive that
|
||||
underly much of Go’s functionality.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Create a new channel with <code>make(chan val-type)</code>.
|
||||
Channels are typed by the values they convey.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">messages</span> <span class="o">:=</span> <span class="nb">make</span><span class="p">(</span><span class="kd">chan</span> <span class="kt">string</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p><em>Send</em> a value into a channel using the <code>channel <-</code>
|
||||
syntax. Here we send <code>"ping"</code> to the <code>messages</code>
|
||||
channel we made above, from a new goroutine.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="k">go</span> <span class="kd">func</span><span class="p">()</span> <span class="p">{</span> <span class="nx">messages</span> <span class="o"><-</span> <span class="s">"ping"</span> <span class="p">}()</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>The <code><-channel</code> syntax <em>receives</em> a value from the
|
||||
channel. Here we’ll receive the <code>"ping"</code> message
|
||||
we sent above and print it out.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre> <span class="nx">msg</span> <span class="o">:=</span> <span class="o"><-</span><span class="nx">messages</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">msg</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>When we run the program the <code>"ping"</code> message is
|
||||
succesfully passed from one goroutine to another via our
|
||||
channel.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run channels.go
|
||||
<span class="go">ping</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>By default sends and receives block until both the
|
||||
sender and receiver are ready. This property allowed
|
||||
us to wait at the end of our program for the <code>"ping"</code>
|
||||
message without having to use any other synchronization.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="channel-buffering">Channel Buffering</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/channels">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
185
public/closing-channels
Normal file
185
public/closing-channels
Normal file
@ -0,0 +1,185 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Closing Channels</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="closing-channels">
|
||||
<h2><a href="./">Go by Example</a>: Closing Channels</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p><em>Closing</em> a channel indicates that no more values
|
||||
will be sent on it. This can be useful to communicate
|
||||
completion to the channel’s receivers.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>In this example we’ll use a <code>jobs</code> channel to
|
||||
communicate work to be done from the <code>main()</code> goroutine
|
||||
to a worker goroutine. When we have no more jobs for
|
||||
the worker we’ll <code>close</code> the <code>jobs</code> channel.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
<span class="nx">jobs</span> <span class="o">:=</span> <span class="nb">make</span><span class="p">(</span><span class="kd">chan</span> <span class="kt">int</span><span class="p">,</span> <span class="mi">5</span><span class="p">)</span>
|
||||
<span class="nx">done</span> <span class="o">:=</span> <span class="nb">make</span><span class="p">(</span><span class="kd">chan</span> <span class="kt">bool</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Here’s the worker goroutine. It repeatedly receives
|
||||
from <code>jobs</code> with <code>j, more := <-jobs</code>. In this
|
||||
special 2-value form of receive, the <code>more</code> value
|
||||
will be <code>false</code> if <code>jobs</code> has been <code>close</code>d and all
|
||||
values in the channel have already been received.
|
||||
We use this to notify on <code>done</code> when we’ve worked
|
||||
all our jobs.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="k">go</span> <span class="kd">func</span><span class="p">()</span> <span class="p">{</span>
|
||||
<span class="k">for</span> <span class="p">{</span>
|
||||
<span class="nx">j</span><span class="p">,</span> <span class="nx">more</span> <span class="o">:=</span> <span class="o"><-</span><span class="nx">jobs</span>
|
||||
<span class="k">if</span> <span class="nx">more</span> <span class="p">{</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"received job"</span><span class="p">,</span> <span class="nx">j</span><span class="p">)</span>
|
||||
<span class="p">}</span> <span class="k">else</span> <span class="p">{</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"received all jobs"</span><span class="p">)</span>
|
||||
<span class="nx">done</span> <span class="o"><-</span> <span class="kc">true</span>
|
||||
<span class="k">return</span>
|
||||
<span class="p">}</span>
|
||||
<span class="p">}</span>
|
||||
<span class="p">}()</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>This sends 3 jobs to the worker over the <code>jobs</code>
|
||||
channel, then closes it.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="k">for</span> <span class="nx">j</span> <span class="o">:=</span> <span class="mi">1</span><span class="p">;</span> <span class="nx">j</span> <span class="o"><=</span> <span class="mi">3</span><span class="p">;</span> <span class="nx">j</span><span class="o">++</span> <span class="p">{</span>
|
||||
<span class="nx">jobs</span> <span class="o"><-</span> <span class="nx">j</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"sent job"</span><span class="p">,</span> <span class="nx">j</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
<span class="nb">close</span><span class="p">(</span><span class="nx">jobs</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"sent all jobs"</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>We await the worker using the
|
||||
<a href="channel-synchronization">synchronization</a> approach
|
||||
we saw earlier.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre> <span class="o"><-</span><span class="nx">done</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run closing-channels.go
|
||||
<span class="go">sent job 1</span>
|
||||
<span class="go">received job 1</span>
|
||||
<span class="go">sent job 2</span>
|
||||
<span class="go">received job 2</span>
|
||||
<span class="go">sent job 3</span>
|
||||
<span class="go">received job 3</span>
|
||||
<span class="go">sent all jobs</span>
|
||||
<span class="go">received all jobs</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>The idea of closed channels leads naturally to our next
|
||||
example: <code>range</code> over channels.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="range-over-channels">Range over Channels</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/closing-channels">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
180
public/closures
Normal file
180
public/closures
Normal file
@ -0,0 +1,180 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Closures</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="closures">
|
||||
<h2><a href="./">Go by Example</a>: Closures</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Go supports <a href="http://en.wikipedia.org/wiki/Anonymous_function"><em>anonymous functions</em></a>,
|
||||
which can form <a href="http://en.wikipedia.org/wiki/Closure_(computer_science)"><em>closures</em></a>.
|
||||
Anonymous functions are useful when you want to define
|
||||
a function inline without having to name it.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>This function <code>intSeq</code> returns another function, which
|
||||
we define anonymously in the body of <code>intSeq</code>. The
|
||||
returned function <em>closes over</em> the variable <code>i</code> to
|
||||
form a closure.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">intSeq</span><span class="p">()</span> <span class="kd">func</span><span class="p">()</span> <span class="kt">int</span> <span class="p">{</span>
|
||||
<span class="nx">i</span> <span class="o">:=</span> <span class="mi">0</span>
|
||||
<span class="k">return</span> <span class="kd">func</span><span class="p">()</span> <span class="kt">int</span> <span class="p">{</span>
|
||||
<span class="nx">i</span> <span class="o">+=</span> <span class="mi">1</span>
|
||||
<span class="k">return</span> <span class="nx">i</span>
|
||||
<span class="p">}</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>We call <code>intSeq</code>, assigning the result (a function)
|
||||
to <code>nextInt</code>. This function value captures its
|
||||
own <code>i</code> value, which will be updated each time
|
||||
we call <code>nextInt</code>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">nextInt</span> <span class="o">:=</span> <span class="nx">intSeq</span><span class="p">()</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>See the effect of the closure by calling <code>nextInt</code>
|
||||
a few times.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">nextInt</span><span class="p">())</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">nextInt</span><span class="p">())</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">nextInt</span><span class="p">())</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>To confirm that the state is unique to that
|
||||
particular function, create and test a new one.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre> <span class="nx">newInts</span> <span class="o">:=</span> <span class="nx">intSeq</span><span class="p">()</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">newInts</span><span class="p">())</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run closures.go
|
||||
<span class="go">1</span>
|
||||
<span class="go">2</span>
|
||||
<span class="go">3</span>
|
||||
<span class="go">1</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>The last feature of functions we’ll look at for now is
|
||||
recursion.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="recursion">Recursion</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/closures">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
348
public/collection-functions
Normal file
348
public/collection-functions
Normal file
@ -0,0 +1,348 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Collection Functions</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="collection-functions">
|
||||
<h2><a href="./">Go by Example</a>: Collection Functions</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>We often need our programs to perform operations on
|
||||
collections of data, like selecting all items that
|
||||
satisfy a given predicate or mapping all items to a new
|
||||
collection with a custom function.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>In some languages it’s idiomatic to use <a href="http://en.wikipedia.org/wiki/Generic_programming">generic</a>
|
||||
data structures and algorithms. Go does not support
|
||||
generics; in Go it’s common to provide collection
|
||||
functions if and when they are specifically needed for
|
||||
your program and data types.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Here are some example collection functions for slices
|
||||
of <code>strings</code>. You can use these examples to build your
|
||||
own functions. Note that in some cases it may be
|
||||
clearest to just inline the collection-manipulating
|
||||
code directly, instead of creating and calling a
|
||||
helper function.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"strings"</span>
|
||||
<span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Returns the first index of the target string <code>t</code>, or
|
||||
-1 if no match is found.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">Index</span><span class="p">(</span><span class="nx">vs</span> <span class="p">[]</span><span class="kt">string</span><span class="p">,</span> <span class="nx">t</span> <span class="kt">string</span><span class="p">)</span> <span class="kt">int</span> <span class="p">{</span>
|
||||
<span class="k">for</span> <span class="nx">i</span><span class="p">,</span> <span class="nx">v</span> <span class="o">:=</span> <span class="k">range</span> <span class="nx">vs</span> <span class="p">{</span>
|
||||
<span class="k">if</span> <span class="nx">v</span> <span class="o">==</span> <span class="nx">t</span> <span class="p">{</span>
|
||||
<span class="k">return</span> <span class="nx">i</span>
|
||||
<span class="p">}</span>
|
||||
<span class="p">}</span>
|
||||
<span class="k">return</span> <span class="o">-</span><span class="mi">1</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Returns <code>true</code> if the target string t is in the
|
||||
slice.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">Include</span><span class="p">(</span><span class="nx">vs</span> <span class="p">[]</span><span class="kt">string</span><span class="p">,</span> <span class="nx">t</span> <span class="kt">string</span><span class="p">)</span> <span class="kt">bool</span> <span class="p">{</span>
|
||||
<span class="k">return</span> <span class="nx">Index</span><span class="p">(</span><span class="nx">vs</span><span class="p">,</span> <span class="nx">t</span><span class="p">)</span> <span class="o">>=</span> <span class="mi">0</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Returns <code>true</code> if one of the strings in the slice
|
||||
satisfies the predicate <code>f</code>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">Any</span><span class="p">(</span><span class="nx">vs</span> <span class="p">[]</span><span class="kt">string</span><span class="p">,</span> <span class="nx">f</span> <span class="kd">func</span><span class="p">(</span><span class="kt">string</span><span class="p">)</span> <span class="kt">bool</span><span class="p">)</span> <span class="kt">bool</span> <span class="p">{</span>
|
||||
<span class="k">for</span> <span class="nx">_</span><span class="p">,</span> <span class="nx">v</span> <span class="o">:=</span> <span class="k">range</span> <span class="nx">vs</span> <span class="p">{</span>
|
||||
<span class="k">if</span> <span class="nx">f</span><span class="p">(</span><span class="nx">v</span><span class="p">)</span> <span class="p">{</span>
|
||||
<span class="k">return</span> <span class="kc">true</span>
|
||||
<span class="p">}</span>
|
||||
<span class="p">}</span>
|
||||
<span class="k">return</span> <span class="kc">false</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Returns <code>true</code> if all of the strings in the slice
|
||||
satisfy the predicate <code>f</code>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">All</span><span class="p">(</span><span class="nx">vs</span> <span class="p">[]</span><span class="kt">string</span><span class="p">,</span> <span class="nx">f</span> <span class="kd">func</span><span class="p">(</span><span class="kt">string</span><span class="p">)</span> <span class="kt">bool</span><span class="p">)</span> <span class="kt">bool</span> <span class="p">{</span>
|
||||
<span class="k">for</span> <span class="nx">_</span><span class="p">,</span> <span class="nx">v</span> <span class="o">:=</span> <span class="k">range</span> <span class="nx">vs</span> <span class="p">{</span>
|
||||
<span class="k">if</span> <span class="p">!</span><span class="nx">f</span><span class="p">(</span><span class="nx">v</span><span class="p">)</span> <span class="p">{</span>
|
||||
<span class="k">return</span> <span class="kc">false</span>
|
||||
<span class="p">}</span>
|
||||
<span class="p">}</span>
|
||||
<span class="k">return</span> <span class="kc">true</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Returns a new slice containing all strings in the
|
||||
slice that satisfy the predicate <code>f</code>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">Filter</span><span class="p">(</span><span class="nx">vs</span> <span class="p">[]</span><span class="kt">string</span><span class="p">,</span> <span class="nx">f</span> <span class="kd">func</span><span class="p">(</span><span class="kt">string</span><span class="p">)</span> <span class="kt">bool</span><span class="p">)</span> <span class="p">[]</span><span class="kt">string</span> <span class="p">{</span>
|
||||
<span class="nx">vsf</span> <span class="o">:=</span> <span class="nb">make</span><span class="p">([]</span><span class="kt">string</span><span class="p">,</span> <span class="mi">0</span><span class="p">)</span>
|
||||
<span class="k">for</span> <span class="nx">_</span><span class="p">,</span> <span class="nx">v</span> <span class="o">:=</span> <span class="k">range</span> <span class="nx">vs</span> <span class="p">{</span>
|
||||
<span class="k">if</span> <span class="nx">f</span><span class="p">(</span><span class="nx">v</span><span class="p">)</span> <span class="p">{</span>
|
||||
<span class="nx">vsf</span> <span class="p">=</span> <span class="nb">append</span><span class="p">(</span><span class="nx">vsf</span><span class="p">,</span> <span class="nx">v</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
<span class="p">}</span>
|
||||
<span class="k">return</span> <span class="nx">vsf</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Returns a new slice containing the results of applying
|
||||
the function <code>f</code> to each string in the original slice.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">Map</span><span class="p">(</span><span class="nx">vs</span> <span class="p">[]</span><span class="kt">string</span><span class="p">,</span> <span class="nx">f</span> <span class="kd">func</span><span class="p">(</span><span class="kt">string</span><span class="p">)</span> <span class="kt">string</span><span class="p">)</span> <span class="p">[]</span><span class="kt">string</span> <span class="p">{</span>
|
||||
<span class="nx">vsm</span> <span class="o">:=</span> <span class="nb">make</span><span class="p">([]</span><span class="kt">string</span><span class="p">,</span> <span class="nb">len</span><span class="p">(</span><span class="nx">vs</span><span class="p">))</span>
|
||||
<span class="k">for</span> <span class="nx">i</span><span class="p">,</span> <span class="nx">v</span> <span class="o">:=</span> <span class="k">range</span> <span class="nx">vs</span> <span class="p">{</span>
|
||||
<span class="nx">vsm</span><span class="p">[</span><span class="nx">i</span><span class="p">]</span> <span class="p">=</span> <span class="nx">f</span><span class="p">(</span><span class="nx">v</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
<span class="k">return</span> <span class="nx">vsm</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Here we try out our various collection functions.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="kd">var</span> <span class="nx">strs</span> <span class="p">=</span> <span class="p">[]</span><span class="kt">string</span><span class="p">{</span><span class="s">"peach"</span><span class="p">,</span> <span class="s">"apple"</span><span class="p">,</span> <span class="s">"pear"</span><span class="p">,</span> <span class="s">"plum"</span><span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">Index</span><span class="p">(</span><span class="nx">strs</span><span class="p">,</span> <span class="s">"pear"</span><span class="p">))</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">Include</span><span class="p">(</span><span class="nx">strs</span><span class="p">,</span> <span class="s">"grape"</span><span class="p">))</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">Any</span><span class="p">(</span><span class="nx">strs</span><span class="p">,</span> <span class="kd">func</span><span class="p">(</span><span class="nx">v</span> <span class="kt">string</span><span class="p">)</span> <span class="kt">bool</span> <span class="p">{</span>
|
||||
<span class="k">return</span> <span class="nx">strings</span><span class="p">.</span><span class="nx">HasPrefix</span><span class="p">(</span><span class="nx">v</span><span class="p">,</span> <span class="s">"p"</span><span class="p">)</span>
|
||||
<span class="p">}))</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">All</span><span class="p">(</span><span class="nx">strs</span><span class="p">,</span> <span class="kd">func</span><span class="p">(</span><span class="nx">v</span> <span class="kt">string</span><span class="p">)</span> <span class="kt">bool</span> <span class="p">{</span>
|
||||
<span class="k">return</span> <span class="nx">strings</span><span class="p">.</span><span class="nx">HasPrefix</span><span class="p">(</span><span class="nx">v</span><span class="p">,</span> <span class="s">"p"</span><span class="p">)</span>
|
||||
<span class="p">}))</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">Filter</span><span class="p">(</span><span class="nx">strs</span><span class="p">,</span> <span class="kd">func</span><span class="p">(</span><span class="nx">v</span> <span class="kt">string</span><span class="p">)</span> <span class="kt">bool</span> <span class="p">{</span>
|
||||
<span class="k">return</span> <span class="nx">strings</span><span class="p">.</span><span class="nx">Contains</span><span class="p">(</span><span class="nx">v</span><span class="p">,</span> <span class="s">"e"</span><span class="p">)</span>
|
||||
<span class="p">}))</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>The above examples all used anonymous functions,
|
||||
but you can also use named functions of the correct
|
||||
type.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">Map</span><span class="p">(</span><span class="nx">strs</span><span class="p">,</span> <span class="nx">strings</span><span class="p">.</span><span class="nx">ToUpper</span><span class="p">))</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre><span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run collection-functions.go
|
||||
<span class="go">2</span>
|
||||
<span class="go">false</span>
|
||||
<span class="go">true</span>
|
||||
<span class="go">false</span>
|
||||
<span class="go">[peach apple pear]</span>
|
||||
<span class="go">[PEACH APPLE PEAR PLUM]</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="string-functions">String Functions</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/collection-functions">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
159
public/command-line-arguments
Normal file
159
public/command-line-arguments
Normal file
@ -0,0 +1,159 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Command-Line Arguments</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
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var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
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|
||||
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|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="command-line-arguments">
|
||||
<h2><a href="./">Go by Example</a>: Command-Line Arguments</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p><a href="http://en.wikipedia.org/wiki/Command-line_interface#Arguments"><em>Command-line arguments</em></a>
|
||||
are a common way to parameterize execution of programs.
|
||||
For example, <code>go run hello.go</code> uses <code>run</code> and
|
||||
<code>hello.go</code> arguments to the <code>go</code> program.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"os"</span>
|
||||
<span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p><code>os.Args</code> provides access to raw command-line
|
||||
arguments. Note that the first value in this slice
|
||||
is the path to the program, and <code>os.Args[1:]</code>
|
||||
holds the arguments to the program.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">argsWithProg</span> <span class="o">:=</span> <span class="nx">os</span><span class="p">.</span><span class="nx">Args</span>
|
||||
<span class="nx">argsWithoutProg</span> <span class="o">:=</span> <span class="nx">os</span><span class="p">.</span><span class="nx">Args</span><span class="p">[</span><span class="mi">1</span><span class="p">:]</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>You can get individual args with normal indexing.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">arg</span> <span class="o">:=</span> <span class="nx">os</span><span class="p">.</span><span class="nx">Args</span><span class="p">[</span><span class="mi">3</span><span class="p">]</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">argsWithProg</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">argsWithoutProg</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">arg</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>To experiment with command-line arguments it’s best to
|
||||
build a binary with <code>go build</code> first.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go build <span class="nb">command</span>-line-arguments.go
|
||||
<span class="gp">$</span> ./command-line-arguments a b c d
|
||||
<span class="go">[./command-line-arguments a b c d] </span>
|
||||
<span class="go">[a b c d]</span>
|
||||
<span class="go">c</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Next we’ll look at more advanced command-line processing
|
||||
with flags.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="command-line-flags">Command-Line Flags</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/command-line-arguments">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
303
public/command-line-flags
Normal file
303
public/command-line-flags
Normal file
@ -0,0 +1,303 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Command-Line Flags</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="command-line-flags">
|
||||
<h2><a href="./">Go by Example</a>: Command-Line Flags</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p><a href="http://en.wikipedia.org/wiki/Command-line_interface#Command-line_option"><em>Command-line flags</em></a>
|
||||
are a common way to specify options for command-line
|
||||
programs. For example, in <code>wc -l</code> the <code>-l</code> is a
|
||||
command-line flag.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Go provides a <code>flag</code> package supporting basic
|
||||
command-line flag parsing. We’ll use this package to
|
||||
implement our example command-line program.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"flag"</span>
|
||||
<span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Basic flag declarations are available for string,
|
||||
integer, and boolean options. Here we declare a
|
||||
string flag <code>word</code> with a default value <code>"foo"</code>
|
||||
and a short description. This <code>flag.String</code> function
|
||||
returns a string pointer (not a string value);
|
||||
we’ll see how to use this pointer below.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">wordPtr</span> <span class="o">:=</span> <span class="nx">flag</span><span class="p">.</span><span class="nx">String</span><span class="p">(</span><span class="s">"word"</span><span class="p">,</span> <span class="s">"foo"</span><span class="p">,</span> <span class="s">"a string"</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>This declares <code>numb</code> and <code>fork</code> flags, using a
|
||||
similar approach to the <code>word</code> flag.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">numbPtr</span> <span class="o">:=</span> <span class="nx">flag</span><span class="p">.</span><span class="nx">Int</span><span class="p">(</span><span class="s">"numb"</span><span class="p">,</span> <span class="mi">42</span><span class="p">,</span> <span class="s">"an int"</span><span class="p">)</span>
|
||||
<span class="nx">boolPtr</span> <span class="o">:=</span> <span class="nx">flag</span><span class="p">.</span><span class="nx">Bool</span><span class="p">(</span><span class="s">"fork"</span><span class="p">,</span> <span class="kc">false</span><span class="p">,</span> <span class="s">"a bool"</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>It’s also possible to declare an option that uses an
|
||||
existing var declared elsewhere in the program.
|
||||
Note that we need to pass in a pointer to the flag
|
||||
declaration function.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="kd">var</span> <span class="nx">svar</span> <span class="kt">string</span>
|
||||
<span class="nx">flag</span><span class="p">.</span><span class="nx">StringVar</span><span class="p">(</span><span class="o">&</span><span class="nx">svar</span><span class="p">,</span> <span class="s">"svar"</span><span class="p">,</span> <span class="s">"bar"</span><span class="p">,</span> <span class="s">"a string var"</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Once all flags are declared, call <code>flag.Parse()</code>
|
||||
to execute the command-line parsing.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">flag</span><span class="p">.</span><span class="nx">Parse</span><span class="p">()</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Here we’ll just dump out the parsed options and
|
||||
any trailing positional arguments. Note that we
|
||||
need to dereference the points with e.g. <code>*wordPtr</code>
|
||||
to get the actual option values.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"word:"</span><span class="p">,</span> <span class="o">*</span><span class="nx">wordPtr</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"numb:"</span><span class="p">,</span> <span class="o">*</span><span class="nx">numbPtr</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"fork:"</span><span class="p">,</span> <span class="o">*</span><span class="nx">boolPtr</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"svar:"</span><span class="p">,</span> <span class="nx">svar</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"tail:"</span><span class="p">,</span> <span class="nx">flag</span><span class="p">.</span><span class="nx">Args</span><span class="p">())</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>To experiment with the command-line flags program it’s
|
||||
best to first compile it and then run the resulting
|
||||
binary directly.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go build <span class="nb">command</span>-line-flags.go
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Try out the built program by first giving it values for
|
||||
all flags.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="gp">$</span> ./command-line-flags -word<span class="o">=</span>opt -numb<span class="o">=</span>7 -fork -svar<span class="o">=</span>flag
|
||||
<span class="go">word: opt</span>
|
||||
<span class="go">numb: 7</span>
|
||||
<span class="go">fork: true</span>
|
||||
<span class="go">svar: flag</span>
|
||||
<span class="go">tail: []</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Note that if you omit flags they automatically take
|
||||
their default values.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="gp">$</span> ./command-line-flags -word<span class="o">=</span>opt
|
||||
<span class="go">word: opt</span>
|
||||
<span class="go">numb: 42</span>
|
||||
<span class="go">fork: false</span>
|
||||
<span class="go">svar: bar</span>
|
||||
<span class="go">tail: []</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Trailing positional arguments can be provided after
|
||||
any flags.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="gp">$</span> ./command-line-flags -word<span class="o">=</span>opt a1 a2 a3
|
||||
<span class="go">word: opt</span>
|
||||
<span class="go">...</span>
|
||||
<span class="go">tail: [a1 a2 a3]</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Note that the <code>flag</code> package requires all flags to
|
||||
appear before positional arguments (otherwise the flags
|
||||
will be interpreted as positional arguments).</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="gp">$</span> ./command-line-flags -word<span class="o">=</span>opt a1 a2 a3 -num<span class="o">=</span>7
|
||||
<span class="go">word: opt</span>
|
||||
<span class="go">numb: 42</span>
|
||||
<span class="go">fork: false</span>
|
||||
<span class="go">svar: bar</span>
|
||||
<span class="go">trailing: [a1 a2 a3 -num=7]</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Use <code>-h</code> or <code>--help</code> flags to get automatically
|
||||
generated help text for the command-line program.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="gp">$</span> ./command-line-flags -h
|
||||
<span class="go">Usage of ./command-line-flags:</span>
|
||||
<span class="go"> -fork=false: a bool</span>
|
||||
<span class="go"> -numb=42: an int</span>
|
||||
<span class="go"> -svar="bar": a string var</span>
|
||||
<span class="go"> -word="foo": a string</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>If you provide a flag that wasn’t specified to the
|
||||
<code>flag</code> package, the program will print an error message
|
||||
an show the help text again.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="gp">$</span> ./command-line-flags -wat
|
||||
<span class="go">flag provided but not defined: -wat</span>
|
||||
<span class="go">Usage of ./command-line-flags:</span>
|
||||
<span class="go">...</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Next we’ll look at environment variables, another common
|
||||
way to parameterize programs.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="environment-variables">Environment Variables</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/command-line-flags">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
171
public/constants
Normal file
171
public/constants
Normal file
@ -0,0 +1,171 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Constants</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="constants">
|
||||
<h2><a href="./">Go by Example</a>: Constants</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Go supports <em>constants</em> of character, string, boolean,
|
||||
and numeric values.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
<span class="kn">import</span> <span class="s">"math"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p><code>const</code> declares a constant value.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">const</span> <span class="nx">s</span> <span class="kt">string</span> <span class="p">=</span> <span class="s">"constant"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">s</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>A <code>const</code> statement can appear anywhere a <code>var</code>
|
||||
statement can.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="kd">const</span> <span class="nx">n</span> <span class="p">=</span> <span class="mi">500000000</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Constant expressions perform arithmetic with
|
||||
arbitrary precision.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="kd">const</span> <span class="nx">d</span> <span class="p">=</span> <span class="mf">3e20</span> <span class="o">/</span> <span class="nx">n</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">d</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>A numeric constant has no type until it’s given
|
||||
one, such as by an explicit cast.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nb">int64</span><span class="p">(</span><span class="nx">d</span><span class="p">))</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>A number can be given a type by using it in a
|
||||
context that requires one, such as a variable
|
||||
assignment or function call. For example, here
|
||||
<code>math.Sin</code> expects a <code>float64</code>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">math</span><span class="p">.</span><span class="nx">Sin</span><span class="p">(</span><span class="nx">n</span><span class="p">))</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run constant.go
|
||||
<span class="go">constant</span>
|
||||
<span class="go">6e+11</span>
|
||||
<span class="go">600000000000</span>
|
||||
<span class="go">-0.28470407323754404</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="for">For</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/constants">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
183
public/defer
Normal file
183
public/defer
Normal file
@ -0,0 +1,183 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Defer</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="defer">
|
||||
<h2><a href="./">Go by Example</a>: Defer</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p><em>Defer</em> is used to ensure that a function call is
|
||||
performed later in a program’s execution, usually for
|
||||
purposes of cleanup. <code>defer</code> is often used where e.g.
|
||||
<code>ensure</code> and <code>finally</code> would be used in other languages.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
<span class="kn">import</span> <span class="s">"os"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Suppose we wanted to create a file, write to it,
|
||||
and then close when we’re done. Here’s how we could
|
||||
do that with <code>defer</code>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Immediately after getting a file object with
|
||||
<code>createFile</code>, we defer the closing of that file
|
||||
with <code>closeFile</code>. This will be executed at the end
|
||||
of the enclosing function (<code>main</code>), after
|
||||
<code>writeFile</code> has finished.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">f</span> <span class="o">:=</span> <span class="nx">createFile</span><span class="p">(</span><span class="s">"/tmp/defer.txt"</span><span class="p">)</span>
|
||||
<span class="k">defer</span> <span class="nx">closeFile</span><span class="p">(</span><span class="nx">f</span><span class="p">)</span>
|
||||
<span class="nx">writeFile</span><span class="p">(</span><span class="nx">f</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">createFile</span><span class="p">(</span><span class="nx">p</span> <span class="kt">string</span><span class="p">)</span> <span class="o">*</span><span class="nx">os</span><span class="p">.</span><span class="nx">File</span> <span class="p">{</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"creating"</span><span class="p">)</span>
|
||||
<span class="nx">f</span><span class="p">,</span> <span class="nx">err</span> <span class="o">:=</span> <span class="nx">os</span><span class="p">.</span><span class="nx">Create</span><span class="p">(</span><span class="nx">p</span><span class="p">)</span>
|
||||
<span class="k">if</span> <span class="nx">err</span> <span class="o">!=</span> <span class="kc">nil</span> <span class="p">{</span>
|
||||
<span class="nb">panic</span><span class="p">(</span><span class="nx">err</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
<span class="k">return</span> <span class="nx">f</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">writeFile</span><span class="p">(</span><span class="nx">f</span> <span class="o">*</span><span class="nx">os</span><span class="p">.</span><span class="nx">File</span><span class="p">)</span> <span class="p">{</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"writing"</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Fprintln</span><span class="p">(</span><span class="nx">f</span><span class="p">,</span> <span class="s">"data"</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">closeFile</span><span class="p">(</span><span class="nx">f</span> <span class="o">*</span><span class="nx">os</span><span class="p">.</span><span class="nx">File</span><span class="p">)</span> <span class="p">{</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"closing"</span><span class="p">)</span>
|
||||
<span class="nx">f</span><span class="p">.</span><span class="nx">Close</span><span class="p">()</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Running the program confirms that the file is closed
|
||||
after being written.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run defer.go
|
||||
<span class="go">creating</span>
|
||||
<span class="go">writing</span>
|
||||
<span class="go">closing</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="collection-functions">Collection Functions</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/defer">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
175
public/environment-variables
Normal file
175
public/environment-variables
Normal file
@ -0,0 +1,175 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Environment Variables</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="environment-variables">
|
||||
<h2><a href="./">Go by Example</a>: Environment Variables</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p><a href="http://en.wikipedia.org/wiki/Environment_variable">Environment variables</a>
|
||||
are a universal mechanism for <a href="http://www.12factor.net/config">conveying configuration
|
||||
information to Unix programs</a>.
|
||||
Let’s look at how to set, get, and list environment variables.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"os"</span>
|
||||
<span class="kn">import</span> <span class="s">"strings"</span>
|
||||
<span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>To set a key/value pair, use <code>os.Setenv</code>. To get a
|
||||
value for a key, use <code>os.Getenv</code>. This will return
|
||||
an empty string if the key isn’t present in the
|
||||
environment.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">os</span><span class="p">.</span><span class="nx">Setenv</span><span class="p">(</span><span class="s">"FOO"</span><span class="p">,</span> <span class="s">"1"</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"FOO:"</span><span class="p">,</span> <span class="nx">os</span><span class="p">.</span><span class="nx">Getenv</span><span class="p">(</span><span class="s">"FOO"</span><span class="p">))</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"BAR:"</span><span class="p">,</span> <span class="nx">os</span><span class="p">.</span><span class="nx">Getenv</span><span class="p">(</span><span class="s">"BAR"</span><span class="p">))</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Use <code>os.Environ</code> to list all key/value pairs in the
|
||||
environment. This returns a slice of strings in the
|
||||
form <code>KEY=value</code>. You can <code>strings.Split</code> them to
|
||||
get the key and value. Here we print all the keys.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">()</span>
|
||||
<span class="k">for</span> <span class="nx">_</span><span class="p">,</span> <span class="nx">e</span> <span class="o">:=</span> <span class="k">range</span> <span class="nx">os</span><span class="p">.</span><span class="nx">Environ</span><span class="p">()</span> <span class="p">{</span>
|
||||
<span class="nx">pair</span> <span class="o">:=</span> <span class="nx">strings</span><span class="p">.</span><span class="nx">Split</span><span class="p">(</span><span class="nx">e</span><span class="p">,</span> <span class="s">"="</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">pair</span><span class="p">[</span><span class="mi">0</span><span class="p">])</span>
|
||||
<span class="p">}</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Running the program shows that we pick up the value
|
||||
value for <code>FOO</code> that we set in the program, but that
|
||||
<code>BAR</code> is empty.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run environment-variables.go
|
||||
<span class="go">FOO: 1</span>
|
||||
<span class="go">BAR: </span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>The list of keys in the environment will depend on your
|
||||
particular machine.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="go">TERM_PROGRAM</span>
|
||||
<span class="go">PATH</span>
|
||||
<span class="go">SHELL</span>
|
||||
<span class="go">...</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>If we set <code>BAR</code> in the environemnt first, the running
|
||||
program picks that value up.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre><span class="gp">$</span> <span class="nv">BAR</span><span class="o">=</span>2 go run environment-variables.go
|
||||
<span class="go">FOO: 1</span>
|
||||
<span class="go">BAR: 2</span>
|
||||
<span class="go">...</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="spawning-processes">Spawning Processes</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/environment-variables">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
166
public/epoch
Normal file
166
public/epoch
Normal file
@ -0,0 +1,166 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Epoch</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="epoch">
|
||||
<h2><a href="./">Go by Example</a>: Epoch</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>A common requirement in programs is getting the number
|
||||
of seconds, milliseconds, or nanoseconds since the
|
||||
<a href="http://en.wikipedia.org/wiki/Unix_time">Unix epoch</a>.
|
||||
Here’s how to do it in Go.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
<span class="kn">import</span> <span class="s">"time"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Use <code>time.Now</code> with <code>Unix</code> or <code>UnixNano</code> to get
|
||||
elapsed time since the Unix epoch in seconds or
|
||||
nanoseconds, respectively.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">now</span> <span class="o">:=</span> <span class="nx">time</span><span class="p">.</span><span class="nx">Now</span><span class="p">()</span>
|
||||
<span class="nx">secs</span> <span class="o">:=</span> <span class="nx">now</span><span class="p">.</span><span class="nx">Unix</span><span class="p">()</span>
|
||||
<span class="nx">nanos</span> <span class="o">:=</span> <span class="nx">now</span><span class="p">.</span><span class="nx">UnixNano</span><span class="p">()</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">now</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Note that there is no <code>UnixMillis</code>, so to get the
|
||||
milliseconds since epoch you’ll need to manually
|
||||
dive from nanoseconds.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">millis</span> <span class="o">:=</span> <span class="nx">nanos</span> <span class="o">/</span> <span class="mi">1000000</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">secs</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">millis</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">nanos</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>You can also convert integer seconds or nanoseconds
|
||||
since the epoch into the corresponding <code>time</code>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">time</span><span class="p">.</span><span class="nx">Unix</span><span class="p">(</span><span class="nx">secs</span><span class="p">,</span> <span class="mi">0</span><span class="p">))</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">time</span><span class="p">.</span><span class="nx">Unix</span><span class="p">(</span><span class="mi">0</span><span class="p">,</span> <span class="nx">nanos</span><span class="p">))</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run epoch.go
|
||||
<span class="go">2012-10-31 16:13:58.292387 +0000 UTC</span>
|
||||
<span class="go">1351700038</span>
|
||||
<span class="go">1351700038292</span>
|
||||
<span class="go">1351700038292387000</span>
|
||||
<span class="go">2012-10-31 16:13:58 +0000 UTC</span>
|
||||
<span class="go">2012-10-31 16:13:58.292387 +0000 UTC</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Next we’ll look at another time-related task: time
|
||||
parsing and formatting.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="time-formatting-parsing">Time Formatting / Parsing</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/epoch">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
281
public/errors
Normal file
281
public/errors
Normal file
@ -0,0 +1,281 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Errors</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="errors">
|
||||
<h2><a href="./">Go by Example</a>: Errors</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>In Go it’s idiomatic to communicate errors via an
|
||||
explicit, separate return value. This contrasts with
|
||||
the exceptions used in languages like Java and Ruby and
|
||||
the overloaded single result / error value sometimes
|
||||
used in C. Go’s approach makes it easy to see which
|
||||
functions return errors and to handle them using the
|
||||
same language constructs employed for any other,
|
||||
non-error tasks.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"errors"</span>
|
||||
<span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>By convention, errors are the last return value and
|
||||
have type <code>error</code>, a built-in interface.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">f1</span><span class="p">(</span><span class="nx">arg</span> <span class="kt">int</span><span class="p">)</span> <span class="p">(</span><span class="kt">int</span><span class="p">,</span> <span class="kt">error</span><span class="p">)</span> <span class="p">{</span>
|
||||
<span class="k">if</span> <span class="nx">arg</span> <span class="o">==</span> <span class="mi">42</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p><code>errors.New</code> constructs a basic <code>error</code> value
|
||||
with the given error message.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="k">return</span> <span class="o">-</span><span class="mi">1</span><span class="p">,</span> <span class="nx">errors</span><span class="p">.</span><span class="nx">New</span><span class="p">(</span><span class="s">"can't work with 42"</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>A nil value in the error position indicates that
|
||||
there was no error.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="k">return</span> <span class="nx">arg</span> <span class="o">+</span> <span class="mi">3</span><span class="p">,</span> <span class="kc">nil</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>It’s possible to use custom types as <code>error</code>s by
|
||||
implementing the <code>Error()</code> method on them. Here’s a
|
||||
variant on the example above that uses a custom type
|
||||
to explicitly represent an argument error.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">type</span> <span class="nx">argError</span> <span class="kd">struct</span> <span class="p">{</span>
|
||||
<span class="nx">arg</span> <span class="kt">int</span>
|
||||
<span class="nx">prob</span> <span class="kt">string</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="p">(</span><span class="nx">e</span> <span class="o">*</span><span class="nx">argError</span><span class="p">)</span> <span class="nx">Error</span><span class="p">()</span> <span class="kt">string</span> <span class="p">{</span>
|
||||
<span class="k">return</span> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Sprintf</span><span class="p">(</span><span class="s">"%d - %s"</span><span class="p">,</span> <span class="nx">e</span><span class="p">.</span><span class="nx">arg</span><span class="p">,</span> <span class="nx">e</span><span class="p">.</span><span class="nx">prob</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">f2</span><span class="p">(</span><span class="nx">arg</span> <span class="kt">int</span><span class="p">)</span> <span class="p">(</span><span class="kt">int</span><span class="p">,</span> <span class="kt">error</span><span class="p">)</span> <span class="p">{</span>
|
||||
<span class="k">if</span> <span class="nx">arg</span> <span class="o">==</span> <span class="mi">42</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>In this case we use <code>&argError</code> syntax to build
|
||||
a new struct, supplying values for the two
|
||||
fields <code>arg</code> and <code>prob</code>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="k">return</span> <span class="o">-</span><span class="mi">1</span><span class="p">,</span> <span class="o">&</span><span class="nx">argError</span><span class="p">{</span><span class="nx">arg</span><span class="p">,</span> <span class="s">"can't work with it"</span><span class="p">}</span>
|
||||
<span class="p">}</span>
|
||||
<span class="k">return</span> <span class="nx">arg</span> <span class="o">+</span> <span class="mi">3</span><span class="p">,</span> <span class="kc">nil</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>The two loops below test out each of our
|
||||
error-returning functions. Note that the use of an
|
||||
inline error check on the <code>if</code> line is a common
|
||||
idiom in Go code.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="k">for</span> <span class="nx">_</span><span class="p">,</span> <span class="nx">i</span> <span class="o">:=</span> <span class="k">range</span> <span class="p">[]</span><span class="kt">int</span><span class="p">{</span><span class="mi">7</span><span class="p">,</span> <span class="mi">42</span><span class="p">}</span> <span class="p">{</span>
|
||||
<span class="k">if</span> <span class="nx">r</span><span class="p">,</span> <span class="nx">e</span> <span class="o">:=</span> <span class="nx">f1</span><span class="p">(</span><span class="nx">i</span><span class="p">);</span> <span class="nx">e</span> <span class="o">!=</span> <span class="kc">nil</span> <span class="p">{</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"f1 failed:"</span><span class="p">,</span> <span class="nx">e</span><span class="p">)</span>
|
||||
<span class="p">}</span> <span class="k">else</span> <span class="p">{</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"f1 worked:"</span><span class="p">,</span> <span class="nx">r</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
<span class="p">}</span>
|
||||
<span class="k">for</span> <span class="nx">_</span><span class="p">,</span> <span class="nx">i</span> <span class="o">:=</span> <span class="k">range</span> <span class="p">[]</span><span class="kt">int</span><span class="p">{</span><span class="mi">7</span><span class="p">,</span> <span class="mi">42</span><span class="p">}</span> <span class="p">{</span>
|
||||
<span class="k">if</span> <span class="nx">r</span><span class="p">,</span> <span class="nx">e</span> <span class="o">:=</span> <span class="nx">f2</span><span class="p">(</span><span class="nx">i</span><span class="p">);</span> <span class="nx">e</span> <span class="o">!=</span> <span class="kc">nil</span> <span class="p">{</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"f2 failed:"</span><span class="p">,</span> <span class="nx">e</span><span class="p">)</span>
|
||||
<span class="p">}</span> <span class="k">else</span> <span class="p">{</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"f2 worked:"</span><span class="p">,</span> <span class="nx">r</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>If you want to programmatically use the data in
|
||||
a custom error, you’ll need to get the error as an
|
||||
instance of the custom error type via type
|
||||
assertion.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre> <span class="nx">_</span><span class="p">,</span> <span class="nx">e</span> <span class="o">:=</span> <span class="nx">f2</span><span class="p">(</span><span class="mi">42</span><span class="p">)</span>
|
||||
<span class="k">if</span> <span class="nx">ae</span><span class="p">,</span> <span class="nx">ok</span> <span class="o">:=</span> <span class="nx">e</span><span class="p">.(</span><span class="o">*</span><span class="nx">argError</span><span class="p">);</span> <span class="nx">ok</span> <span class="p">{</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">ae</span><span class="p">.</span><span class="nx">arg</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">ae</span><span class="p">.</span><span class="nx">prob</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run errors.go
|
||||
<span class="go">f1 worked: 10</span>
|
||||
<span class="go">f1 failed: can't work with 42</span>
|
||||
<span class="go">f2 worked: 10</span>
|
||||
<span class="go">f2 failed: 42 - can't work with it</span>
|
||||
<span class="go">42</span>
|
||||
<span class="go">can't work with it</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>See this <a href="http://blog.golang.org/2011/07/error-handling-and-go.html">great post</a>
|
||||
on the Go blog for more on error handling.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="goroutines">Goroutines</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/errors">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
190
public/execing-processes
Normal file
190
public/execing-processes
Normal file
@ -0,0 +1,190 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Exec'ing Processes</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="execing-processes">
|
||||
<h2><a href="./">Go by Example</a>: Exec'ing Processes</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>In the previous example we looked at
|
||||
<a href="spawning-processes">spawning external processes</a>. We
|
||||
do this when we need an external process accessible to
|
||||
a running Go process. Sometimes we just want to
|
||||
completely replace the current Go process with another
|
||||
(perhaps non-Go) one. To do this we’ll use Go’s
|
||||
implementation of the classic
|
||||
<a href="http://en.wikipedia.org/wiki/Exec_(operating_system)"><code>exec</code></a>
|
||||
function.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"syscall"</span>
|
||||
<span class="kn">import</span> <span class="s">"os"</span>
|
||||
<span class="kn">import</span> <span class="s">"os/exec"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>For our example we’ll exec <code>ls</code>. Go requires an
|
||||
abolute path to the binary we want to execute, so
|
||||
we’ll use <code>exec.LookPath</code> to find it (probably
|
||||
<code>/bin/ls</code>).</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">binary</span><span class="p">,</span> <span class="nx">lookErr</span> <span class="o">:=</span> <span class="nx">exec</span><span class="p">.</span><span class="nx">LookPath</span><span class="p">(</span><span class="s">"ls"</span><span class="p">)</span>
|
||||
<span class="k">if</span> <span class="nx">lookErr</span> <span class="o">!=</span> <span class="kc">nil</span> <span class="p">{</span>
|
||||
<span class="nb">panic</span><span class="p">(</span><span class="nx">lookErr</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p><code>Exec</code> requires arguments in slice form (as
|
||||
apposed to one big string). We’ll give <code>ls</code> a few
|
||||
common arguments.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">args</span> <span class="o">:=</span> <span class="p">[]</span><span class="kt">string</span><span class="p">{</span><span class="s">"-a"</span><span class="p">,</span> <span class="s">"-l"</span><span class="p">,</span> <span class="s">"-h"</span><span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p><code>Exec</code> also needs a set of <a href="environment-variables">environment variables</a>
|
||||
to use. Here we just provide our current
|
||||
environment.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">env</span> <span class="o">:=</span> <span class="nx">os</span><span class="p">.</span><span class="nx">Environ</span><span class="p">()</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Here’s the actual <code>os.Exec</code> call. If this call is
|
||||
succesful, the execution of our process will end
|
||||
here and be replaced by the <code>/bin/ls -a -l -h</code>
|
||||
process. If there is an error we’ll get a return
|
||||
value.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre> <span class="nx">execErr</span> <span class="o">:=</span> <span class="nx">syscall</span><span class="p">.</span><span class="nx">Exec</span><span class="p">(</span><span class="nx">binary</span><span class="p">,</span> <span class="nx">args</span><span class="p">,</span> <span class="nx">env</span><span class="p">)</span>
|
||||
<span class="k">if</span> <span class="nx">execErr</span> <span class="o">!=</span> <span class="kc">nil</span> <span class="p">{</span>
|
||||
<span class="nb">panic</span><span class="p">(</span><span class="nx">execErr</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>When we run our program it is replaced by <code>ls</code>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run execing-processes.go
|
||||
<span class="go">total 16</span>
|
||||
<span class="go">drwxr-xr-x 4 mark 136B Oct 3 16:29 .</span>
|
||||
<span class="go">drwxr-xr-x 91 mark 3.0K Oct 3 12:50 ..</span>
|
||||
<span class="go">-rw-r--r-- 1 mark 1.3K Oct 3 16:28 execing-processes.go</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Note that Go does not offer a classic Unix <code>fork</code>
|
||||
function. Usually this isn’t an issue though, since
|
||||
starting goroutines, spawning processes, and exec’ing
|
||||
processes covers most use cases for <code>fork</code>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="signals">Signals</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/execing-processes">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
162
public/exit
Normal file
162
public/exit
Normal file
@ -0,0 +1,162 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Exit</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="exit">
|
||||
<h2><a href="./">Go by Example</a>: Exit</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Use <code>os.Exit</code> to immediately exit with a given
|
||||
status.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
<span class="kn">import</span> <span class="s">"os"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p><code>defer</code>s will <em>not</em> be run when using <code>os.Exit</code>, so
|
||||
this <code>fmt.Println</code> will never be called.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="k">defer</span> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"!"</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Exit with status 3.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">os</span><span class="p">.</span><span class="nx">Exit</span><span class="p">(</span><span class="mi">3</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Note that unlike e.g. C, Go does not use an integer
|
||||
return value from <code>main</code> to indicate exit status. If
|
||||
you’d like to exit with a non-zero status you should
|
||||
use <code>os.Exit</code>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>If you run <code>exit.go</code> using <code>go run</code>, the exit
|
||||
will be picked up by <code>go</code> and printed.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run exit.go
|
||||
<span class="go">exit status 3</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>By building and executing a binary you can see
|
||||
the status in the terminal.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go build exit.go
|
||||
<span class="gp">$</span> ./exit
|
||||
<span class="gp">$</span> <span class="nb">echo</span> <span class="nv">$?</span>
|
||||
<span class="go">3</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Note that the <code>!</code> from our program never got printed.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/exit">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
BIN
public/favicon.ico
Normal file
BIN
public/favicon.ico
Normal file
Binary file not shown.
|
After Width: | Height: | Size: 97 KiB |
164
public/for
Normal file
164
public/for
Normal file
@ -0,0 +1,164 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: For</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="for">
|
||||
<h2><a href="./">Go by Example</a>: For</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p><code>for</code> is Go’s only looping construct. Here are
|
||||
three basic types of <code>for</code> loops.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>The most basic type, with a single condition.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">i</span> <span class="o">:=</span> <span class="mi">1</span>
|
||||
<span class="k">for</span> <span class="nx">i</span> <span class="o"><=</span> <span class="mi">3</span> <span class="p">{</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">i</span><span class="p">)</span>
|
||||
<span class="nx">i</span> <span class="p">=</span> <span class="nx">i</span> <span class="o">+</span> <span class="mi">1</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>A classic initial/condition/after <code>for</code> loop.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="k">for</span> <span class="nx">j</span> <span class="o">:=</span> <span class="mi">7</span><span class="p">;</span> <span class="nx">j</span> <span class="o"><=</span> <span class="mi">9</span><span class="p">;</span> <span class="nx">j</span><span class="o">++</span> <span class="p">{</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">j</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p><code>for</code> without a condition will loop repeatedly
|
||||
until you <code>break</code> out of the loop or <code>return</code> from
|
||||
the enclosing function.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre> <span class="k">for</span> <span class="p">{</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"loop"</span><span class="p">)</span>
|
||||
<span class="k">break</span>
|
||||
<span class="p">}</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run <span class="k">for</span>.go
|
||||
<span class="go">1</span>
|
||||
<span class="go">2</span>
|
||||
<span class="go">3</span>
|
||||
<span class="go">7</span>
|
||||
<span class="go">8</span>
|
||||
<span class="go">9</span>
|
||||
<span class="go">loop</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>We’ll see some other <code>for</code> forms latter when we look at
|
||||
<code>range</code> statements, channels, and other data
|
||||
structures.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="if-else">If/Else</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/for">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
152
public/functions
Normal file
152
public/functions
Normal file
@ -0,0 +1,152 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Functions</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="functions">
|
||||
<h2><a href="./">Go by Example</a>: Functions</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p><em>Functions</em> are central in Go. We’ll learn about
|
||||
functions with a few different examples.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Here’s a function that takes two <code>int</code>s and returns
|
||||
their sum as an <code>int</code>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">plus</span><span class="p">(</span><span class="nx">a</span> <span class="kt">int</span><span class="p">,</span> <span class="nx">b</span> <span class="kt">int</span><span class="p">)</span> <span class="kt">int</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Go requires explicit returns, i.e. it won’t
|
||||
automatically return the value of the last
|
||||
expression.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="k">return</span> <span class="nx">a</span> <span class="o">+</span> <span class="nx">b</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Call a function just as you’d expect, with
|
||||
<code>name(args)</code>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre> <span class="nx">res</span> <span class="o">:=</span> <span class="nx">plus</span><span class="p">(</span><span class="mi">1</span><span class="p">,</span> <span class="mi">2</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"1+2 ="</span><span class="p">,</span> <span class="nx">res</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run functions.go
|
||||
<span class="go">1+2 = 3</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>There are several other features to Go functions. One is
|
||||
multiple return values, which we’ll look at next.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="multiple-return-values">Multiple Return Values</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/functions">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
196
public/goroutines
Normal file
196
public/goroutines
Normal file
@ -0,0 +1,196 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Goroutines</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="goroutines">
|
||||
<h2><a href="./">Go by Example</a>: Goroutines</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>A <em>goroutine</em> is a lightweight thread of execution.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">f</span><span class="p">(</span><span class="nx">from</span> <span class="kt">string</span><span class="p">)</span> <span class="p">{</span>
|
||||
<span class="k">for</span> <span class="nx">i</span> <span class="o">:=</span> <span class="mi">0</span><span class="p">;</span> <span class="nx">i</span> <span class="p"><</span> <span class="mi">3</span><span class="p">;</span> <span class="nx">i</span><span class="o">++</span> <span class="p">{</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">from</span><span class="p">,</span> <span class="s">":"</span><span class="p">,</span> <span class="nx">i</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Suppose we have a function call <code>f(s)</code>. Here’s how
|
||||
we’d call that in the usual way, running it
|
||||
synchronously.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">f</span><span class="p">(</span><span class="s">"direct"</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>To invoke this function in a goroutine, use
|
||||
<code>go f(s)</code>. This new goroutine will execute
|
||||
concurrently with the calling one.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="k">go</span> <span class="nx">f</span><span class="p">(</span><span class="s">"goroutine"</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>You can also start a goroutine for an anonymous
|
||||
function call.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="k">go</span> <span class="kd">func</span><span class="p">(</span><span class="nx">msg</span> <span class="kt">string</span><span class="p">)</span> <span class="p">{</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">msg</span><span class="p">)</span>
|
||||
<span class="p">}(</span><span class="s">"going"</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Our two goroutines are running asynchronously in
|
||||
separate goroutines now, so execution falls through
|
||||
to here. This <code>Scanln</code> code requires we press a key
|
||||
before the program exits.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre> <span class="kd">var</span> <span class="nx">input</span> <span class="kt">string</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Scanln</span><span class="p">(</span><span class="o">&</span><span class="nx">input</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"done"</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>When we run this program, we see the output of the
|
||||
blocking call first, then the interleaved output of the
|
||||
two gouroutines. This interleaving reflects the
|
||||
goroutines being run concurrently by the Go runtime.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run goroutines.go
|
||||
<span class="go">direct : 0</span>
|
||||
<span class="go">direct : 1</span>
|
||||
<span class="go">direct : 2</span>
|
||||
<span class="go">goroutine : 0</span>
|
||||
<span class="go">going</span>
|
||||
<span class="go">goroutine : 1</span>
|
||||
<span class="go">goroutine : 2</span>
|
||||
<span class="go"><enter></span>
|
||||
<span class="go">done</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Next we’ll look at a complement to goroutines in
|
||||
concurrent Go programs: channels.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="channels">Channels</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/goroutines">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
132
public/hello-world
Normal file
132
public/hello-world
Normal file
@ -0,0 +1,132 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Hello World</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="hello-world">
|
||||
<h2><a href="./">Go by Example</a>: Hello World</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Our first program will print the classic “hello world”
|
||||
message. Here’s the full source code.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"hello world"</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>To run the program, put the code in <code>hello-world.go</code> and
|
||||
use <code>go run</code>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run hello-world.go
|
||||
<span class="go">hello world</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Sometimes we’ll want to build our programs into
|
||||
binaries. We can do this using <code>go build</code>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go build hello-world.go
|
||||
<span class="gp">$</span> ls
|
||||
<span class="go">hello-world hello-world.go</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>We can then execute the built binary directly.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="gp">$</span> ./hello-world
|
||||
<span class="go">hello world</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Now that we can run and build basic Go programs, let’s
|
||||
learn more about the language.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="values">Values</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/hello-world">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
174
public/if-else
Normal file
174
public/if-else
Normal file
@ -0,0 +1,174 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: If/Else</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="if-else">
|
||||
<h2><a href="./">Go by Example</a>: If/Else</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Branching with <code>if</code> and <code>else</code> in Go is
|
||||
straight-forward.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Here’s a basic example.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="k">if</span> <span class="mi">7</span><span class="o">%</span><span class="mi">2</span> <span class="o">==</span> <span class="mi">0</span> <span class="p">{</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"7 is even"</span><span class="p">)</span>
|
||||
<span class="p">}</span> <span class="k">else</span> <span class="p">{</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"7 is odd"</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>You can have an <code>if</code> statement without an else.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="k">if</span> <span class="mi">8</span><span class="o">%</span><span class="mi">4</span> <span class="o">==</span> <span class="mi">0</span> <span class="p">{</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"8 is divisible by 4"</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>A statement can proceed conditionals; any variables
|
||||
declared in this statement are available in all
|
||||
branches.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="k">if</span> <span class="nx">num</span> <span class="o">:=</span> <span class="mi">9</span><span class="p">;</span> <span class="nx">num</span> <span class="p"><</span> <span class="mi">0</span> <span class="p">{</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">num</span><span class="p">,</span> <span class="s">"is negative"</span><span class="p">)</span>
|
||||
<span class="p">}</span> <span class="k">else</span> <span class="k">if</span> <span class="nx">num</span> <span class="p"><</span> <span class="mi">10</span> <span class="p">{</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">num</span><span class="p">,</span> <span class="s">"has 1 digit"</span><span class="p">)</span>
|
||||
<span class="p">}</span> <span class="k">else</span> <span class="p">{</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">num</span><span class="p">,</span> <span class="s">"has multiple digits"</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Note that you don’t need parentheses around conditions
|
||||
in Go, but that the brackets are required.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run <span class="k">if</span>-else.go
|
||||
<span class="go">7 is odd</span>
|
||||
<span class="go">8 is divisible by 4</span>
|
||||
<span class="go">9 has 1 digit</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>There is no <a href="http://en.wikipedia.org/wiki/%3F:">ternary if</a>
|
||||
in Go, so you’ll need to use a full <code>if</code> statement even
|
||||
for basic conditions.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="switch">Switch</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/if-else">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
174
public/index.html
Normal file
174
public/index.html
Normal file
@ -0,0 +1,174 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div id="intro">
|
||||
<h2><a href="./">Go by Example</a></h2>
|
||||
<p>
|
||||
<a href="http://golang.org">Go</a> is an
|
||||
open source programming language designed for
|
||||
building simple, fast, and reliable software.
|
||||
</p>
|
||||
|
||||
<p>
|
||||
<em>Go by Example</em> is a hands-on introduction
|
||||
to Go using annotated example programs. Check out
|
||||
the <a href="/hello-world">first example</a> or
|
||||
browse the full list below.
|
||||
</p>
|
||||
|
||||
<ul>
|
||||
|
||||
<li><a href="hello-world">Hello World</a></li>
|
||||
|
||||
<li><a href="values">Values</a></li>
|
||||
|
||||
<li><a href="variables">Variables</a></li>
|
||||
|
||||
<li><a href="constants">Constants</a></li>
|
||||
|
||||
<li><a href="for">For</a></li>
|
||||
|
||||
<li><a href="if-else">If/Else</a></li>
|
||||
|
||||
<li><a href="switch">Switch</a></li>
|
||||
|
||||
<li><a href="arrays">Arrays</a></li>
|
||||
|
||||
<li><a href="slices">Slices</a></li>
|
||||
|
||||
<li><a href="maps">Maps</a></li>
|
||||
|
||||
<li><a href="range">Range</a></li>
|
||||
|
||||
<li><a href="functions">Functions</a></li>
|
||||
|
||||
<li><a href="multiple-return-values">Multiple Return Values</a></li>
|
||||
|
||||
<li><a href="variadic-functions">Variadic Functions</a></li>
|
||||
|
||||
<li><a href="closures">Closures</a></li>
|
||||
|
||||
<li><a href="recursion">Recursion</a></li>
|
||||
|
||||
<li><a href="pointers">Pointers</a></li>
|
||||
|
||||
<li><a href="structs">Structs</a></li>
|
||||
|
||||
<li><a href="methods">Methods</a></li>
|
||||
|
||||
<li><a href="interfaces">Interfaces</a></li>
|
||||
|
||||
<li><a href="errors">Errors</a></li>
|
||||
|
||||
<li><a href="goroutines">Goroutines</a></li>
|
||||
|
||||
<li><a href="channels">Channels</a></li>
|
||||
|
||||
<li><a href="channel-buffering">Channel Buffering</a></li>
|
||||
|
||||
<li><a href="channel-synchronization">Channel Synchronization</a></li>
|
||||
|
||||
<li><a href="channel-directions">Channel Directions</a></li>
|
||||
|
||||
<li><a href="select">Select</a></li>
|
||||
|
||||
<li><a href="timeouts">Timeouts</a></li>
|
||||
|
||||
<li><a href="non-blocking-channel-operations">Non-Blocking Channel Operations</a></li>
|
||||
|
||||
<li><a href="closing-channels">Closing Channels</a></li>
|
||||
|
||||
<li><a href="range-over-channels">Range over Channels</a></li>
|
||||
|
||||
<li><a href="timers">Timers</a></li>
|
||||
|
||||
<li><a href="tickers">Tickers</a></li>
|
||||
|
||||
<li><a href="worker-pools">Worker Pools</a></li>
|
||||
|
||||
<li><a href="rate-limiting">Rate Limiting</a></li>
|
||||
|
||||
<li><a href="atomic-counters">Atomic Counters</a></li>
|
||||
|
||||
<li><a href="mutexes">Mutexes</a></li>
|
||||
|
||||
<li><a href="stateful-goroutines">Stateful Goroutines</a></li>
|
||||
|
||||
<li><a href="sorting">Sorting</a></li>
|
||||
|
||||
<li><a href="sorting-by-functions">Sorting by Functions</a></li>
|
||||
|
||||
<li><a href="panic">Panic</a></li>
|
||||
|
||||
<li><a href="defer">Defer</a></li>
|
||||
|
||||
<li><a href="collection-functions">Collection Functions</a></li>
|
||||
|
||||
<li><a href="string-functions">String Functions</a></li>
|
||||
|
||||
<li><a href="string-formatting">String Formatting</a></li>
|
||||
|
||||
<li><a href="regular-expressions">Regular Expressions</a></li>
|
||||
|
||||
<li><a href="json">JSON</a></li>
|
||||
|
||||
<li><a href="time">Time</a></li>
|
||||
|
||||
<li><a href="epoch">Epoch</a></li>
|
||||
|
||||
<li><a href="time-formatting-parsing">Time Formatting / Parsing</a></li>
|
||||
|
||||
<li><a href="random-numbers">Random Numbers</a></li>
|
||||
|
||||
<li><a href="number-parsing">Number Parsing</a></li>
|
||||
|
||||
<li><a href="url-parsing">URL Parsing</a></li>
|
||||
|
||||
<li><a href="sha1-hashes">SHA1 Hashes</a></li>
|
||||
|
||||
<li><a href="base64-encoding">Base64 Encoding</a></li>
|
||||
|
||||
<li><a href="reading-files">Reading Files</a></li>
|
||||
|
||||
<li><a href="writing-files">Writing Files</a></li>
|
||||
|
||||
<li><a href="line-filters">Line Filters</a></li>
|
||||
|
||||
<li><a href="command-line-arguments">Command-Line Arguments</a></li>
|
||||
|
||||
<li><a href="command-line-flags">Command-Line Flags</a></li>
|
||||
|
||||
<li><a href="environment-variables">Environment Variables</a></li>
|
||||
|
||||
<li><a href="spawning-processes">Spawning Processes</a></li>
|
||||
|
||||
<li><a href="execing-processes">Exec'ing Processes</a></li>
|
||||
|
||||
<li><a href="signals">Signals</a></li>
|
||||
|
||||
<li><a href="exit">Exit</a></li>
|
||||
|
||||
</ul>
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
222
public/interfaces
Normal file
222
public/interfaces
Normal file
@ -0,0 +1,222 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Interfaces</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="interfaces">
|
||||
<h2><a href="./">Go by Example</a>: Interfaces</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p><em>Interfaces</em> are named collections of method
|
||||
signatures.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
<span class="kn">import</span> <span class="s">"math"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Here’s a basic interface for geometric shapes.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">type</span> <span class="nx">geometry</span> <span class="kd">interface</span> <span class="p">{</span>
|
||||
<span class="nx">area</span><span class="p">()</span> <span class="kt">float64</span>
|
||||
<span class="nx">perim</span><span class="p">()</span> <span class="kt">float64</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>For our example we’ll implement this interface on
|
||||
<code>square</code> and <code>circle</code> types.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">type</span> <span class="nx">square</span> <span class="kd">struct</span> <span class="p">{</span>
|
||||
<span class="nx">width</span><span class="p">,</span> <span class="nx">height</span> <span class="kt">float64</span>
|
||||
<span class="p">}</span>
|
||||
<span class="kd">type</span> <span class="nx">circle</span> <span class="kd">struct</span> <span class="p">{</span>
|
||||
<span class="nx">radius</span> <span class="kt">float64</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>To implement an interface in Go, we just need to
|
||||
implement all the methods in the interface. Here we
|
||||
implement <code>geometry</code> on <code>square</code>s.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="p">(</span><span class="nx">s</span> <span class="nx">square</span><span class="p">)</span> <span class="nx">area</span><span class="p">()</span> <span class="kt">float64</span> <span class="p">{</span>
|
||||
<span class="k">return</span> <span class="nx">s</span><span class="p">.</span><span class="nx">width</span> <span class="o">*</span> <span class="nx">s</span><span class="p">.</span><span class="nx">height</span>
|
||||
<span class="p">}</span>
|
||||
<span class="kd">func</span> <span class="p">(</span><span class="nx">s</span> <span class="nx">square</span><span class="p">)</span> <span class="nx">perim</span><span class="p">()</span> <span class="kt">float64</span> <span class="p">{</span>
|
||||
<span class="k">return</span> <span class="mi">2</span><span class="o">*</span><span class="nx">s</span><span class="p">.</span><span class="nx">width</span> <span class="o">+</span> <span class="mi">2</span><span class="o">*</span><span class="nx">s</span><span class="p">.</span><span class="nx">height</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>The implementation for <code>circle</code>s.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="p">(</span><span class="nx">c</span> <span class="nx">circle</span><span class="p">)</span> <span class="nx">area</span><span class="p">()</span> <span class="kt">float64</span> <span class="p">{</span>
|
||||
<span class="k">return</span> <span class="nx">math</span><span class="p">.</span><span class="nx">Pi</span> <span class="o">*</span> <span class="nx">c</span><span class="p">.</span><span class="nx">radius</span> <span class="o">*</span> <span class="nx">c</span><span class="p">.</span><span class="nx">radius</span>
|
||||
<span class="p">}</span>
|
||||
<span class="kd">func</span> <span class="p">(</span><span class="nx">c</span> <span class="nx">circle</span><span class="p">)</span> <span class="nx">perim</span><span class="p">()</span> <span class="kt">float64</span> <span class="p">{</span>
|
||||
<span class="k">return</span> <span class="mi">2</span> <span class="o">*</span> <span class="nx">math</span><span class="p">.</span><span class="nx">Pi</span> <span class="o">*</span> <span class="nx">c</span><span class="p">.</span><span class="nx">radius</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>If a variable has an interface type, then we can call
|
||||
methods that are in the named interface. Here’s a
|
||||
generic <code>measure</code> function taking advantage of this
|
||||
to work on any <code>geometry</code>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">measure</span><span class="p">(</span><span class="nx">g</span> <span class="nx">geometry</span><span class="p">)</span> <span class="p">{</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">g</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">g</span><span class="p">.</span><span class="nx">area</span><span class="p">())</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">g</span><span class="p">.</span><span class="nx">perim</span><span class="p">())</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
<span class="nx">s</span> <span class="o">:=</span> <span class="nx">square</span><span class="p">{</span><span class="nx">width</span><span class="p">:</span> <span class="mi">3</span><span class="p">,</span> <span class="nx">height</span><span class="p">:</span> <span class="mi">4</span><span class="p">}</span>
|
||||
<span class="nx">c</span> <span class="o">:=</span> <span class="nx">circle</span><span class="p">{</span><span class="nx">radius</span><span class="p">:</span> <span class="mi">5</span><span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>The <code>circle</code> and <code>square</code> struct types both
|
||||
implement the <code>geometry</code> interface so we can use
|
||||
instances of
|
||||
these structs as arguments to measure.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre> <span class="nx">measure</span><span class="p">(</span><span class="nx">s</span><span class="p">)</span>
|
||||
<span class="nx">measure</span><span class="p">(</span><span class="nx">c</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run interfaces.go
|
||||
<span class="go">{3 4}</span>
|
||||
<span class="go">12</span>
|
||||
<span class="go">14</span>
|
||||
<span class="go">{5}</span>
|
||||
<span class="go">78.53981633974483</span>
|
||||
<span class="go">31.41592653589793</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>To learn more about Go’s interfaces, check out this
|
||||
<a href="http://jordanorelli.tumblr.com/post/32665860244/how-to-use-interfaces-in-go">great blog post</a>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="errors">Errors</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/interfaces">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
379
public/json
Normal file
379
public/json
Normal file
@ -0,0 +1,379 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: JSON</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="json">
|
||||
<h2><a href="./">Go by Example</a>: JSON</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Go offers built-in support for JSON encoding and
|
||||
decoding, including to and from built-in and custom
|
||||
data types.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"encoding/json"</span>
|
||||
<span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
<span class="kn">import</span> <span class="s">"os"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>We’ll use these two structs to demonstrate encoding and
|
||||
decoding of custom types below.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">type</span> <span class="nx">Response1</span> <span class="kd">struct</span> <span class="p">{</span>
|
||||
<span class="nx">Page</span> <span class="kt">int</span>
|
||||
<span class="nx">Fruits</span> <span class="p">[]</span><span class="kt">string</span>
|
||||
<span class="p">}</span>
|
||||
<span class="kd">type</span> <span class="nx">Response2</span> <span class="kd">struct</span> <span class="p">{</span>
|
||||
<span class="nx">Page</span> <span class="kt">int</span> <span class="s">`json:"page"`</span>
|
||||
<span class="nx">Fruits</span> <span class="p">[]</span><span class="kt">string</span> <span class="s">`json:"fruits"`</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>First we’ll look at encoding basic data types to
|
||||
JSON strings. Here are some examples for atomic
|
||||
values.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">bolB</span><span class="p">,</span> <span class="nx">_</span> <span class="o">:=</span> <span class="nx">json</span><span class="p">.</span><span class="nx">Marshal</span><span class="p">(</span><span class="kc">true</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nb">string</span><span class="p">(</span><span class="nx">bolB</span><span class="p">))</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">intB</span><span class="p">,</span> <span class="nx">_</span> <span class="o">:=</span> <span class="nx">json</span><span class="p">.</span><span class="nx">Marshal</span><span class="p">(</span><span class="mi">1</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nb">string</span><span class="p">(</span><span class="nx">intB</span><span class="p">))</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fltB</span><span class="p">,</span> <span class="nx">_</span> <span class="o">:=</span> <span class="nx">json</span><span class="p">.</span><span class="nx">Marshal</span><span class="p">(</span><span class="mf">2.34</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nb">string</span><span class="p">(</span><span class="nx">fltB</span><span class="p">))</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">strB</span><span class="p">,</span> <span class="nx">_</span> <span class="o">:=</span> <span class="nx">json</span><span class="p">.</span><span class="nx">Marshal</span><span class="p">(</span><span class="s">"gopher"</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nb">string</span><span class="p">(</span><span class="nx">strB</span><span class="p">))</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>And here are some for slices and maps, which encode
|
||||
to JSON arrays and objects as you’d expect.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">slcD</span> <span class="o">:=</span> <span class="p">[]</span><span class="kt">string</span><span class="p">{</span><span class="s">"apple"</span><span class="p">,</span> <span class="s">"peach"</span><span class="p">,</span> <span class="s">"pear"</span><span class="p">}</span>
|
||||
<span class="nx">slcB</span><span class="p">,</span> <span class="nx">_</span> <span class="o">:=</span> <span class="nx">json</span><span class="p">.</span><span class="nx">Marshal</span><span class="p">(</span><span class="nx">slcD</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nb">string</span><span class="p">(</span><span class="nx">slcB</span><span class="p">))</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">mapD</span> <span class="o">:=</span> <span class="kd">map</span><span class="p">[</span><span class="kt">string</span><span class="p">]</span><span class="kt">int</span><span class="p">{</span><span class="s">"apple"</span><span class="p">:</span> <span class="mi">5</span><span class="p">,</span> <span class="s">"lettuce"</span><span class="p">:</span> <span class="mi">7</span><span class="p">}</span>
|
||||
<span class="nx">mapB</span><span class="p">,</span> <span class="nx">_</span> <span class="o">:=</span> <span class="nx">json</span><span class="p">.</span><span class="nx">Marshal</span><span class="p">(</span><span class="nx">mapD</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nb">string</span><span class="p">(</span><span class="nx">mapB</span><span class="p">))</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>The JSON package can automatically encode your
|
||||
custom data types. It will only include exported
|
||||
fields in the encoded output and will by default
|
||||
use those names as the JSON keys.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">res1D</span> <span class="o">:=</span> <span class="o">&</span><span class="nx">Response1</span><span class="p">{</span>
|
||||
<span class="nx">Page</span><span class="p">:</span> <span class="mi">1</span><span class="p">,</span>
|
||||
<span class="nx">Fruits</span><span class="p">:</span> <span class="p">[]</span><span class="kt">string</span><span class="p">{</span><span class="s">"apple"</span><span class="p">,</span> <span class="s">"peach"</span><span class="p">,</span> <span class="s">"pear"</span><span class="p">}}</span>
|
||||
<span class="nx">res1B</span><span class="p">,</span> <span class="nx">_</span> <span class="o">:=</span> <span class="nx">json</span><span class="p">.</span><span class="nx">Marshal</span><span class="p">(</span><span class="nx">res1D</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nb">string</span><span class="p">(</span><span class="nx">res1B</span><span class="p">))</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>You can use tags on struct field declarations
|
||||
to customize the encoded JSON key names. Check the
|
||||
definition of <code>Response2</code> above to see an example
|
||||
of such tags.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">res2D</span> <span class="o">:=</span> <span class="o">&</span><span class="nx">Response2</span><span class="p">{</span>
|
||||
<span class="nx">Page</span><span class="p">:</span> <span class="mi">1</span><span class="p">,</span>
|
||||
<span class="nx">Fruits</span><span class="p">:</span> <span class="p">[]</span><span class="kt">string</span><span class="p">{</span><span class="s">"apple"</span><span class="p">,</span> <span class="s">"peach"</span><span class="p">,</span> <span class="s">"pear"</span><span class="p">}}</span>
|
||||
<span class="nx">res2B</span><span class="p">,</span> <span class="nx">_</span> <span class="o">:=</span> <span class="nx">json</span><span class="p">.</span><span class="nx">Marshal</span><span class="p">(</span><span class="nx">res2D</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nb">string</span><span class="p">(</span><span class="nx">res2B</span><span class="p">))</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Now let’s look at decoding JSON data into Go
|
||||
values. Here’s an example for a generic data
|
||||
structure.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">byt</span> <span class="o">:=</span> <span class="p">[]</span><span class="nb">byte</span><span class="p">(</span><span class="s">`{"num":6.0,"strs":["a","b"]}`</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>We need to provide a variable where the JSON
|
||||
package can put the decoded data. This
|
||||
<code>map[string]interface{}</code> will hold a map of strings
|
||||
to arbitrary data types.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="kd">var</span> <span class="nx">dat</span> <span class="kd">map</span><span class="p">[</span><span class="kt">string</span><span class="p">]</span><span class="kd">interface</span><span class="p">{}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Here’s the actual decoding, and a check for
|
||||
associated errors.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="k">if</span> <span class="nx">err</span> <span class="o">:=</span> <span class="nx">json</span><span class="p">.</span><span class="nx">Unmarshal</span><span class="p">(</span><span class="nx">byt</span><span class="p">,</span> <span class="o">&</span><span class="nx">dat</span><span class="p">);</span> <span class="nx">err</span> <span class="o">!=</span> <span class="kc">nil</span> <span class="p">{</span>
|
||||
<span class="nb">panic</span><span class="p">(</span><span class="nx">err</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">dat</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>In order to use the values in the decoded map,
|
||||
we’ll need to cast them to their appropriate type.
|
||||
For example here we cast the value in <code>num</code> to
|
||||
the expected <code>float64</code> type.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">num</span> <span class="o">:=</span> <span class="nx">dat</span><span class="p">[</span><span class="s">"num"</span><span class="p">].(</span><span class="kt">float64</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">num</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Accessing nested data requires a series of
|
||||
casts.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">strs</span> <span class="o">:=</span> <span class="nx">dat</span><span class="p">[</span><span class="s">"strs"</span><span class="p">].([]</span><span class="kd">interface</span><span class="p">{})</span>
|
||||
<span class="nx">str1</span> <span class="o">:=</span> <span class="nx">strs</span><span class="p">[</span><span class="mi">0</span><span class="p">].(</span><span class="kt">string</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">str1</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>We can also decode JSON into custom data types.
|
||||
This has the advantages of adding additional
|
||||
type-safety to our programs and eliminating the
|
||||
need for type assertions when accessing the decoded
|
||||
data.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">str</span> <span class="o">:=</span> <span class="s">`{"page": 1, "fruits": ["apple", "peach"]}`</span>
|
||||
<span class="nx">res</span> <span class="o">:=</span> <span class="o">&</span><span class="nx">Response2</span><span class="p">{}</span>
|
||||
<span class="nx">json</span><span class="p">.</span><span class="nx">Unmarshal</span><span class="p">([]</span><span class="nb">byte</span><span class="p">(</span><span class="nx">str</span><span class="p">),</span> <span class="o">&</span><span class="nx">res</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">res</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">res</span><span class="p">.</span><span class="nx">Fruits</span><span class="p">[</span><span class="mi">0</span><span class="p">])</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>In the examples above we always used bytes and
|
||||
strings as intermediates between the data and
|
||||
JSON representation on standard out. We can also
|
||||
stream JSON encodings directly to <code>os.Writer</code>s like
|
||||
<code>os.Stdout</code> or even HTTP response bodies.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre> <span class="nx">enc</span> <span class="o">:=</span> <span class="nx">json</span><span class="p">.</span><span class="nx">NewEncoder</span><span class="p">(</span><span class="nx">os</span><span class="p">.</span><span class="nx">Stdout</span><span class="p">)</span>
|
||||
<span class="nx">d</span> <span class="o">:=</span> <span class="kd">map</span><span class="p">[</span><span class="kt">string</span><span class="p">]</span><span class="kt">int</span><span class="p">{</span><span class="s">"apple"</span><span class="p">:</span> <span class="mi">5</span><span class="p">,</span> <span class="s">"lettuce"</span><span class="p">:</span> <span class="mi">7</span><span class="p">}</span>
|
||||
<span class="nx">enc</span><span class="p">.</span><span class="nx">Encode</span><span class="p">(</span><span class="nx">d</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run json.go
|
||||
<span class="go">true</span>
|
||||
<span class="go">1</span>
|
||||
<span class="go">2.34</span>
|
||||
<span class="go">"gopher"</span>
|
||||
<span class="go">["apple","peach","pear"]</span>
|
||||
<span class="go">{"apple":5,"lettuce":7}</span>
|
||||
<span class="go">{"Page":1,"Fruits":["apple","peach","pear"]}</span>
|
||||
<span class="go">{"page":1,"fruits":["apple","peach","pear"]}</span>
|
||||
<span class="go">map[num:6 strs:[a b]]</span>
|
||||
<span class="go">6</span>
|
||||
<span class="go">a</span>
|
||||
<span class="go">&{1 [apple peach]}</span>
|
||||
<span class="go">apple</span>
|
||||
<span class="go">{"apple":5,"lettuce":7}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>We’ve covered the basic of JSON in Go here, but check
|
||||
out the <a href="http://blog.golang.org/2011/01/json-and-go.html">JSON and Go</a>
|
||||
blog post and <a href="http://golang.org/pkg/encoding/json/">JSON package docs</a>
|
||||
for more.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="time">Time</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/json">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
207
public/line-filters
Normal file
207
public/line-filters
Normal file
@ -0,0 +1,207 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Line Filters</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="line-filters">
|
||||
<h2><a href="./">Go by Example</a>: Line Filters</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>A <em>line filter</em> is a common type of program that reads
|
||||
input on stdin, processes it, and then prints some
|
||||
derived result to stdout. <code>grep</code> and <code>sed</code> are common
|
||||
line filters.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Here’s an example line filter in Go that writes a
|
||||
capitalized version of all input text. You can use this
|
||||
pattern to write your own Go line filters.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="p">(</span>
|
||||
<span class="s">"bufio"</span>
|
||||
<span class="s">"fmt"</span>
|
||||
<span class="s">"io"</span>
|
||||
<span class="s">"os"</span>
|
||||
<span class="s">"strings"</span>
|
||||
<span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Wrapping the unbuffered <code>os.Stdin</code> with a buffered
|
||||
reader gives us a convenient <code>ReadString</code> method
|
||||
that we’ll use to read input line-by-line.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">rdr</span> <span class="o">:=</span> <span class="nx">bufio</span><span class="p">.</span><span class="nx">NewReader</span><span class="p">(</span><span class="nx">os</span><span class="p">.</span><span class="nx">Stdin</span><span class="p">)</span>
|
||||
<span class="nx">out</span> <span class="o">:=</span> <span class="nx">os</span><span class="p">.</span><span class="nx">Stdout</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p><code>ReadString</code> returns the next string from the
|
||||
input up to the given separator byte. We give the
|
||||
newline byte <code>'\n'</code> as our separator so we’ll get
|
||||
successive input lines.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="k">for</span> <span class="p">{</span>
|
||||
<span class="k">switch</span> <span class="nx">line</span><span class="p">,</span> <span class="nx">err</span> <span class="o">:=</span> <span class="nx">rdr</span><span class="p">.</span><span class="nx">ReadString</span><span class="p">(</span><span class="sc">'\n'</span><span class="p">);</span> <span class="nx">err</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>If the read succeeded (the read <code>err</code> is nil),
|
||||
write out out the uppercased line. Check for an
|
||||
error on this write as we do on the read.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="k">case</span> <span class="kc">nil</span><span class="p">:</span>
|
||||
<span class="nx">ucl</span> <span class="o">:=</span> <span class="nx">strings</span><span class="p">.</span><span class="nx">ToUpper</span><span class="p">(</span><span class="nx">line</span><span class="p">)</span>
|
||||
<span class="k">if</span> <span class="nx">_</span><span class="p">,</span> <span class="nx">err</span> <span class="p">=</span> <span class="nx">out</span><span class="p">.</span><span class="nx">WriteString</span><span class="p">(</span><span class="nx">ucl</span><span class="p">);</span> <span class="nx">err</span> <span class="o">!=</span> <span class="kc">nil</span> <span class="p">{</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Fprintln</span><span class="p">(</span><span class="nx">os</span><span class="p">.</span><span class="nx">Stderr</span><span class="p">,</span> <span class="s">"error:"</span><span class="p">,</span> <span class="nx">err</span><span class="p">)</span>
|
||||
<span class="nx">os</span><span class="p">.</span><span class="nx">Exit</span><span class="p">(</span><span class="mi">1</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>The <code>EOF</code> error is expected when we reach the
|
||||
end of input, so exit gracefully in that case.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="k">case</span> <span class="nx">io</span><span class="p">.</span><span class="nx">EOF</span><span class="p">:</span>
|
||||
<span class="nx">os</span><span class="p">.</span><span class="nx">Exit</span><span class="p">(</span><span class="mi">0</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Otherwise there’s a problem; print the
|
||||
error and exit with non-zero status.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre> <span class="k">default</span><span class="p">:</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Fprintln</span><span class="p">(</span><span class="nx">os</span><span class="p">.</span><span class="nx">Stderr</span><span class="p">,</span> <span class="s">"error:"</span><span class="p">,</span> <span class="nx">err</span><span class="p">)</span>
|
||||
<span class="nx">os</span><span class="p">.</span><span class="nx">Exit</span><span class="p">(</span><span class="mi">1</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
<span class="p">}</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>To try out our line filter, first make a file with a few
|
||||
lowercase lines.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="gp">$</span> <span class="nb">echo</span> <span class="s1">'hello'</span> > /tmp/lines
|
||||
<span class="gp">$</span> <span class="nb">echo</span> <span class="s1">'filter'</span> >> /tmp/lines
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Then use the line filter to get uppercase lines.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre><span class="gp">$</span> cat /tmp/lines | go run line-filters.go
|
||||
<span class="go">HELLO</span>
|
||||
<span class="go">FILTER</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="command-line-arguments">Command-Line Arguments</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/line-filters">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
217
public/maps
Normal file
217
public/maps
Normal file
@ -0,0 +1,217 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Maps</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="maps">
|
||||
<h2><a href="./">Go by Example</a>: Maps</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p><em>Maps</em> are Go’s built-in <a href="http://en.wikipedia.org/wiki/Associative_array">associative data type</a>
|
||||
(sometimes called <em>hashes</em> or <em>dicts</em> in other languages).</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>To create an empty map, use the builtin <code>make</code>:
|
||||
<code>make(map[key-type]val-type)</code>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">m</span> <span class="o">:=</span> <span class="nb">make</span><span class="p">(</span><span class="kd">map</span><span class="p">[</span><span class="kt">string</span><span class="p">]</span><span class="kt">int</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Set key/value pairs using typical <code>name[key] = val</code>
|
||||
syntax.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">m</span><span class="p">[</span><span class="s">"k1"</span><span class="p">]</span> <span class="p">=</span> <span class="mi">7</span>
|
||||
<span class="nx">m</span><span class="p">[</span><span class="s">"k2"</span><span class="p">]</span> <span class="p">=</span> <span class="mi">13</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Printing a map with e.g. <code>Println</code> will show all of
|
||||
its key/value pairs.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"map:"</span><span class="p">,</span> <span class="nx">m</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Get a value for a key with <code>name[key]</code>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">v1</span> <span class="o">:=</span> <span class="nx">m</span><span class="p">[</span><span class="s">"k1"</span><span class="p">]</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"v1: "</span><span class="p">,</span> <span class="nx">v1</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>The builtin <code>len</code> returns the number of key/value
|
||||
pairs when called on a map.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"len:"</span><span class="p">,</span> <span class="nb">len</span><span class="p">(</span><span class="nx">m</span><span class="p">))</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>The builtin <code>delete</code> removes key/value pairs from
|
||||
a map.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nb">delete</span><span class="p">(</span><span class="nx">m</span><span class="p">,</span> <span class="s">"k2"</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"map:"</span><span class="p">,</span> <span class="nx">m</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>The optional second return value when getting a
|
||||
value from a map indiciates if the key was present
|
||||
in the map. This can be used to disambiguate
|
||||
between missing keys and keys with zero values
|
||||
like <code>0</code> or <code>""</code>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">_</span><span class="p">,</span> <span class="nx">prs</span> <span class="o">:=</span> <span class="nx">m</span><span class="p">[</span><span class="s">"k2"</span><span class="p">]</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"prs:"</span><span class="p">,</span> <span class="nx">prs</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>You can also declare and initialize a new map in
|
||||
the same line with this syntax.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre> <span class="nx">n</span> <span class="o">:=</span> <span class="kd">map</span><span class="p">[</span><span class="kt">string</span><span class="p">]</span><span class="kt">int</span><span class="p">{</span><span class="s">"foo"</span><span class="p">:</span> <span class="mi">1</span><span class="p">,</span> <span class="s">"bar"</span><span class="p">:</span> <span class="mi">2</span><span class="p">}</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"map:"</span><span class="p">,</span> <span class="nx">n</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Note that maps appear in the form <code>map[k:v k:v]</code> when
|
||||
printed with <code>fmt.Println</code>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run maps.go
|
||||
<span class="go">map: map[k1:7 k2:13]</span>
|
||||
<span class="go">v1: 7</span>
|
||||
<span class="go">len: 2</span>
|
||||
<span class="go">map: map[k1:7]</span>
|
||||
<span class="go">prs: false</span>
|
||||
<span class="go">map: map[foo:1 bar:2]</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="range">Range</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/maps">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
186
public/methods
Normal file
186
public/methods
Normal file
@ -0,0 +1,186 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Methods</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="methods">
|
||||
<h2><a href="./">Go by Example</a>: Methods</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Go supports <em>methods</em> defined on struct types.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">type</span> <span class="nx">rect</span> <span class="kd">struct</span> <span class="p">{</span>
|
||||
<span class="nx">width</span><span class="p">,</span> <span class="nx">height</span> <span class="kt">int</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>This <code>area</code> method has a <em>receiver type</em> of <code>*rect</code>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="p">(</span><span class="nx">r</span> <span class="o">*</span><span class="nx">rect</span><span class="p">)</span> <span class="nx">area</span><span class="p">()</span> <span class="kt">int</span> <span class="p">{</span>
|
||||
<span class="k">return</span> <span class="nx">r</span><span class="p">.</span><span class="nx">width</span> <span class="o">*</span> <span class="nx">r</span><span class="p">.</span><span class="nx">height</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Methods can be defined for either pointer or value
|
||||
receiver types. Here’s an example of a value receiver.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="p">(</span><span class="nx">r</span> <span class="nx">rect</span><span class="p">)</span> <span class="nx">perim</span><span class="p">()</span> <span class="kt">int</span> <span class="p">{</span>
|
||||
<span class="k">return</span> <span class="mi">2</span><span class="o">*</span><span class="nx">r</span><span class="p">.</span><span class="nx">width</span> <span class="o">+</span> <span class="mi">2</span><span class="o">*</span><span class="nx">r</span><span class="p">.</span><span class="nx">height</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
<span class="nx">r</span> <span class="o">:=</span> <span class="nx">rect</span><span class="p">{</span><span class="nx">width</span><span class="p">:</span> <span class="mi">10</span><span class="p">,</span> <span class="nx">height</span><span class="p">:</span> <span class="mi">5</span><span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Here we call the 2 methods defined for our struct.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"area: "</span><span class="p">,</span> <span class="nx">r</span><span class="p">.</span><span class="nx">area</span><span class="p">())</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"perim:"</span><span class="p">,</span> <span class="nx">r</span><span class="p">.</span><span class="nx">perim</span><span class="p">())</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Go automatically handles conversion between values
|
||||
and pointers for method calls. You may want to use
|
||||
a pointer receiver type to avoid copying on method
|
||||
calls or to allow the method to mutate the
|
||||
receiving struct.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre> <span class="nx">rp</span> <span class="o">:=</span> <span class="o">&</span><span class="nx">r</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"area: "</span><span class="p">,</span> <span class="nx">rp</span><span class="p">.</span><span class="nx">area</span><span class="p">())</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"perim:"</span><span class="p">,</span> <span class="nx">rp</span><span class="p">.</span><span class="nx">perim</span><span class="p">())</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run methods.go
|
||||
<span class="go">area: 50</span>
|
||||
<span class="go">perim: 30</span>
|
||||
<span class="go">area: 50</span>
|
||||
<span class="go">perim: 30</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Next we’ll look at Go’s mechanism for grouping and
|
||||
naming related sets of methods: interfaces.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="interfaces">Interfaces</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/methods">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
157
public/multiple-return-values
Normal file
157
public/multiple-return-values
Normal file
@ -0,0 +1,157 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Multiple Return Values</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="multiple-return-values">
|
||||
<h2><a href="./">Go by Example</a>: Multiple Return Values</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Go has built-in support for <em>multiple return values</em>.
|
||||
This feature is used often in idiomatic Go, for example
|
||||
to return both result and error values from a function.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>The <code>(int, int)</code> in this function signature shows that
|
||||
the function returns 2 <code>int</code>s.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">vals</span><span class="p">()</span> <span class="p">(</span><span class="kt">int</span><span class="p">,</span> <span class="kt">int</span><span class="p">)</span> <span class="p">{</span>
|
||||
<span class="k">return</span> <span class="mi">3</span><span class="p">,</span> <span class="mi">7</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Here we use the 2 different return values from the
|
||||
call with <em>multiple assignment</em>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">a</span><span class="p">,</span> <span class="nx">b</span> <span class="o">:=</span> <span class="nx">vals</span><span class="p">()</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">a</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">b</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>If you only want a subset of the returned values,
|
||||
use the blank identifier <code>_</code>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre> <span class="nx">_</span><span class="p">,</span> <span class="nx">c</span> <span class="o">:=</span> <span class="nx">vals</span><span class="p">()</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">c</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run multiple-return-values.go
|
||||
<span class="go">3</span>
|
||||
<span class="go">7</span>
|
||||
<span class="go">7</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Accepting a variable number of arguments is another nice
|
||||
feature of Go functions; we’ll look at this next.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="variadic-functions">Variadic Functions</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/multiple-return-values">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
285
public/mutexes
Normal file
285
public/mutexes
Normal file
@ -0,0 +1,285 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Mutexes</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
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_gaq.push(['_trackPageview']);
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(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
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ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
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|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="mutexes">
|
||||
<h2><a href="./">Go by Example</a>: Mutexes</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>In the previous example we saw how to manage simple
|
||||
counter state using atomic operations. For more complex
|
||||
state we can use a <em><a href="http://en.wikipedia.org/wiki/Mutual_exclusion">mutex</a></em>
|
||||
to safely access data across multiple goroutines.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="p">(</span>
|
||||
<span class="s">"fmt"</span>
|
||||
<span class="s">"math/rand"</span>
|
||||
<span class="s">"runtime"</span>
|
||||
<span class="s">"sync"</span>
|
||||
<span class="s">"sync/atomic"</span>
|
||||
<span class="s">"time"</span>
|
||||
<span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>For our example the <code>state</code> will be a map.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="kd">var</span> <span class="nx">state</span> <span class="p">=</span> <span class="nb">make</span><span class="p">(</span><span class="kd">map</span><span class="p">[</span><span class="kt">int</span><span class="p">]</span><span class="kt">int</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>This <code>mutex</code> will synchronize access to <code>state</code>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="kd">var</span> <span class="nx">mutex</span> <span class="p">=</span> <span class="o">&</span><span class="nx">sync</span><span class="p">.</span><span class="nx">Mutex</span><span class="p">{}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>To compare the mutex-based approach with another
|
||||
we’ll see later, <code>ops</code> will count how many
|
||||
operations we perform against the state.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="kd">var</span> <span class="nx">ops</span> <span class="kt">int64</span> <span class="p">=</span> <span class="mi">0</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Here we start 100 goroutines to execute repeated
|
||||
reads against the state.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="k">for</span> <span class="nx">r</span> <span class="o">:=</span> <span class="mi">0</span><span class="p">;</span> <span class="nx">r</span> <span class="p"><</span> <span class="mi">100</span><span class="p">;</span> <span class="nx">r</span><span class="o">++</span> <span class="p">{</span>
|
||||
<span class="k">go</span> <span class="kd">func</span><span class="p">()</span> <span class="p">{</span>
|
||||
<span class="nx">total</span> <span class="o">:=</span> <span class="mi">0</span>
|
||||
<span class="k">for</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>For each read we pick a key to access,
|
||||
<code>Lock()</code> the <code>mutex</code> to ensure
|
||||
exclusive access to the <code>state</code>, read
|
||||
the value at the chosen key,
|
||||
<code>Unlock()</code> the mutex, and increment
|
||||
the <code>ops</code> count.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">key</span> <span class="o">:=</span> <span class="nx">rand</span><span class="p">.</span><span class="nx">Intn</span><span class="p">(</span><span class="mi">5</span><span class="p">)</span>
|
||||
<span class="nx">mutex</span><span class="p">.</span><span class="nx">Lock</span><span class="p">()</span>
|
||||
<span class="nx">total</span> <span class="o">+=</span> <span class="nx">state</span><span class="p">[</span><span class="nx">key</span><span class="p">]</span>
|
||||
<span class="nx">mutex</span><span class="p">.</span><span class="nx">Unlock</span><span class="p">()</span>
|
||||
<span class="nx">atomic</span><span class="p">.</span><span class="nx">AddInt64</span><span class="p">(</span><span class="o">&</span><span class="nx">ops</span><span class="p">,</span> <span class="mi">1</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>In order to ensure that this goroutine
|
||||
doesn’t starve the scheduler, we explicitly
|
||||
yield after each operation with
|
||||
<code>runtime.Gosched()</code>. This yielding is
|
||||
handled automatically with e.g. every
|
||||
channel operation and for blocking
|
||||
calls like <code>time.Sleep</code>, but in this
|
||||
case we need to do it manually.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">runtime</span><span class="p">.</span><span class="nx">Gosched</span><span class="p">()</span>
|
||||
<span class="p">}</span>
|
||||
<span class="p">}()</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>We’ll also start 10 goroutines to simulate writes,
|
||||
using the same pattern we did for reads.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="k">for</span> <span class="nx">w</span> <span class="o">:=</span> <span class="mi">0</span><span class="p">;</span> <span class="nx">w</span> <span class="p"><</span> <span class="mi">10</span><span class="p">;</span> <span class="nx">w</span><span class="o">++</span> <span class="p">{</span>
|
||||
<span class="k">go</span> <span class="kd">func</span><span class="p">()</span> <span class="p">{</span>
|
||||
<span class="k">for</span> <span class="p">{</span>
|
||||
<span class="nx">key</span> <span class="o">:=</span> <span class="nx">rand</span><span class="p">.</span><span class="nx">Intn</span><span class="p">(</span><span class="mi">5</span><span class="p">)</span>
|
||||
<span class="nx">val</span> <span class="o">:=</span> <span class="nx">rand</span><span class="p">.</span><span class="nx">Intn</span><span class="p">(</span><span class="mi">100</span><span class="p">)</span>
|
||||
<span class="nx">mutex</span><span class="p">.</span><span class="nx">Lock</span><span class="p">()</span>
|
||||
<span class="nx">state</span><span class="p">[</span><span class="nx">key</span><span class="p">]</span> <span class="p">=</span> <span class="nx">val</span>
|
||||
<span class="nx">mutex</span><span class="p">.</span><span class="nx">Unlock</span><span class="p">()</span>
|
||||
<span class="nx">atomic</span><span class="p">.</span><span class="nx">AddInt64</span><span class="p">(</span><span class="o">&</span><span class="nx">ops</span><span class="p">,</span> <span class="mi">1</span><span class="p">)</span>
|
||||
<span class="nx">runtime</span><span class="p">.</span><span class="nx">Gosched</span><span class="p">()</span>
|
||||
<span class="p">}</span>
|
||||
<span class="p">}()</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Let the 110 goroutines work on the <code>state</code> and
|
||||
<code>mutex</code> for a second.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">time</span><span class="p">.</span><span class="nx">Sleep</span><span class="p">(</span><span class="nx">time</span><span class="p">.</span><span class="nx">Second</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Take and report a final operations count.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">opsFinal</span> <span class="o">:=</span> <span class="nx">atomic</span><span class="p">.</span><span class="nx">LoadInt64</span><span class="p">(</span><span class="o">&</span><span class="nx">ops</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"ops:"</span><span class="p">,</span> <span class="nx">opsFinal</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>With a final lock of <code>state</code>, show how it ended up.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre> <span class="nx">mutex</span><span class="p">.</span><span class="nx">Lock</span><span class="p">()</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"state:"</span><span class="p">,</span> <span class="nx">state</span><span class="p">)</span>
|
||||
<span class="nx">mutex</span><span class="p">.</span><span class="nx">Unlock</span><span class="p">()</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Running the program shows that we executed about
|
||||
3,500,000 operations against our <code>mutex</code>-synchronized
|
||||
<code>state</code>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run mutexes.go
|
||||
<span class="go">ops: 3598302</span>
|
||||
<span class="go">state: map[1:38 4:98 2:23 3:85 0:44]</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Next we’ll look at implementing this same state
|
||||
management task using only goroutines and channels.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="stateful-goroutines">Stateful Goroutines</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/mutexes">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
165
public/non-blocking-channel-operations
Normal file
165
public/non-blocking-channel-operations
Normal file
@ -0,0 +1,165 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Non-Blocking Channel Operations</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="non-blocking-channel-operations">
|
||||
<h2><a href="./">Go by Example</a>: Non-Blocking Channel Operations</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Basic sends and receives on channels are blocking.
|
||||
However, we can use <code>select</code> with a <code>default</code> clause to
|
||||
implement <em>non-blocking</em> sends, receives, and even
|
||||
non-blocking multi-way <code>select</code>s.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
<span class="nx">messages</span> <span class="o">:=</span> <span class="nb">make</span><span class="p">(</span><span class="kd">chan</span> <span class="kt">string</span><span class="p">)</span>
|
||||
<span class="nx">signals</span> <span class="o">:=</span> <span class="nb">make</span><span class="p">(</span><span class="kd">chan</span> <span class="kt">bool</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Here’s a non-blocking receive. If a value is
|
||||
available on <code>messages</code> then <code>select</code> will take
|
||||
the <code><-messages</code> <code>case</code> with that value. If not
|
||||
it will immediately take the <code>default</code> case.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="k">select</span> <span class="p">{</span>
|
||||
<span class="k">case</span> <span class="nx">msg</span> <span class="o">:=</span> <span class="o"><-</span><span class="nx">messages</span><span class="p">:</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"received message"</span><span class="p">,</span> <span class="nx">msg</span><span class="p">)</span>
|
||||
<span class="k">default</span><span class="p">:</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"no message received"</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>A non-blocking send works similarly.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">msg</span> <span class="o">:=</span> <span class="s">"hi"</span>
|
||||
<span class="k">select</span> <span class="p">{</span>
|
||||
<span class="k">case</span> <span class="nx">messages</span> <span class="o"><-</span> <span class="nx">msg</span><span class="p">:</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"sent message"</span><span class="p">,</span> <span class="nx">msg</span><span class="p">)</span>
|
||||
<span class="k">default</span><span class="p">:</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"no message sent"</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>We can use multiple <code>case</code>s above the <code>default</code>
|
||||
clause to implement a multi-way non-blocking
|
||||
select. Here we attempt non-blocking receives
|
||||
on both <code>messages</code> and <code>signals</code>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre> <span class="k">select</span> <span class="p">{</span>
|
||||
<span class="k">case</span> <span class="nx">msg</span> <span class="o">:=</span> <span class="o"><-</span><span class="nx">messages</span><span class="p">:</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"received message"</span><span class="p">,</span> <span class="nx">msg</span><span class="p">)</span>
|
||||
<span class="k">case</span> <span class="nx">sig</span> <span class="o">:=</span> <span class="o"><-</span><span class="nx">signals</span><span class="p">:</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"received signal"</span><span class="p">,</span> <span class="nx">sig</span><span class="p">)</span>
|
||||
<span class="k">default</span><span class="p">:</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"no activity"</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run non-blocking-channel-operations.go
|
||||
<span class="go">no message received</span>
|
||||
<span class="go">no message sent</span>
|
||||
<span class="go">no activity</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="closing-channels">Closing Channels</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/non-blocking-channel-operations">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
199
public/number-parsing
Normal file
199
public/number-parsing
Normal file
@ -0,0 +1,199 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Number Parsing</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="number-parsing">
|
||||
<h2><a href="./">Go by Example</a>: Number Parsing</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Parsing numbers from strings is a basic but common task
|
||||
in many programs; here’s how to do it in Go.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>The built-in package <code>strconv</code> provides the number
|
||||
parsing.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"strconv"</span>
|
||||
<span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>With <code>ParseFloat</code>, this <code>64</code> tells how many bits of
|
||||
precision to parse.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">f</span><span class="p">,</span> <span class="nx">_</span> <span class="o">:=</span> <span class="nx">strconv</span><span class="p">.</span><span class="nx">ParseFloat</span><span class="p">(</span><span class="s">"1.234"</span><span class="p">,</span> <span class="mi">64</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">f</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>For <code>ParseInt</code>, the <code>0</code> means infer the base from
|
||||
the string. <code>64</code> requires that the result fit in 64
|
||||
bits.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">i</span><span class="p">,</span> <span class="nx">_</span> <span class="o">:=</span> <span class="nx">strconv</span><span class="p">.</span><span class="nx">ParseInt</span><span class="p">(</span><span class="s">"123"</span><span class="p">,</span> <span class="mi">0</span><span class="p">,</span> <span class="mi">64</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">i</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p><code>ParseInt</code> will recognize hex-formatted numbers.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">d</span><span class="p">,</span> <span class="nx">_</span> <span class="o">:=</span> <span class="nx">strconv</span><span class="p">.</span><span class="nx">ParseInt</span><span class="p">(</span><span class="s">"0x1c8"</span><span class="p">,</span> <span class="mi">0</span><span class="p">,</span> <span class="mi">64</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">d</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>A <code>ParseUint</code> is also available.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">u</span><span class="p">,</span> <span class="nx">_</span> <span class="o">:=</span> <span class="nx">strconv</span><span class="p">.</span><span class="nx">ParseUint</span><span class="p">(</span><span class="s">"789"</span><span class="p">,</span> <span class="mi">0</span><span class="p">,</span> <span class="mi">64</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">u</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p><code>Atoi</code> is a convenience function for basic base-10
|
||||
<code>int</code> parsing.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">k</span><span class="p">,</span> <span class="nx">_</span> <span class="o">:=</span> <span class="nx">strconv</span><span class="p">.</span><span class="nx">Atoi</span><span class="p">(</span><span class="s">"135"</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">k</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Parse functions return an error on bad input.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre> <span class="nx">_</span><span class="p">,</span> <span class="nx">e</span> <span class="o">:=</span> <span class="nx">strconv</span><span class="p">.</span><span class="nx">Atoi</span><span class="p">(</span><span class="s">"wat"</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">e</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run number-parsing.go
|
||||
<span class="go">1.234</span>
|
||||
<span class="go">123</span>
|
||||
<span class="go">456</span>
|
||||
<span class="go">789</span>
|
||||
<span class="go">135</span>
|
||||
<span class="go">strconv.ParseInt: parsing "wat": invalid syntax</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Next we’ll look at another common parsing task: URLs.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="url-parsing">URL Parsing</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/number-parsing">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
163
public/panic
Normal file
163
public/panic
Normal file
@ -0,0 +1,163 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Panic</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="panic">
|
||||
<h2><a href="./">Go by Example</a>: Panic</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>A <code>panic</code> typically means something went unexpectedly
|
||||
wrong. Mostly we use it to fail fast on errors that
|
||||
shouldn’t occur during normal operation, or that we
|
||||
aren’t prepared to handle gracefully.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"os"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>We’ll use panic throughout this site to check for
|
||||
unexpected errors. This is the only program on the
|
||||
site designed to panic.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nb">panic</span><span class="p">(</span><span class="s">"a problem"</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>A common use of panic is to abort if a function
|
||||
returns an error value that we don’t know how to
|
||||
(or want to) handle. Here’s an example of
|
||||
<code>panic</code>king if we get an unexpected error when creating a new file.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre> <span class="nx">_</span><span class="p">,</span> <span class="nx">err</span> <span class="o">:=</span> <span class="nx">os</span><span class="p">.</span><span class="nx">Create</span><span class="p">(</span><span class="s">"/tmp/file"</span><span class="p">)</span>
|
||||
<span class="k">if</span> <span class="nx">err</span> <span class="o">!=</span> <span class="kc">nil</span> <span class="p">{</span>
|
||||
<span class="nb">panic</span><span class="p">(</span><span class="nx">err</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Running this program will cause it to panic, print
|
||||
an error message and goroutine traces, and exit with
|
||||
a non-zero status.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run panic.go
|
||||
<span class="go">panic: a problem</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="go">goroutine 1 [running]:</span>
|
||||
<span class="go">main.main()</span>
|
||||
<span class="go"> /.../panic.go:12 +0x47</span>
|
||||
<span class="go">...</span>
|
||||
<span class="go">exit status 2</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Note that unlike some languages which use exceptions
|
||||
for handling of many errors, in Go it is idiomatic
|
||||
to use error-indicating return values wherever possible.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="defer">Defer</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/panic">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
183
public/pointers
Normal file
183
public/pointers
Normal file
@ -0,0 +1,183 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Pointers</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="pointers">
|
||||
<h2><a href="./">Go by Example</a>: Pointers</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Go supports <em><a href="http://en.wikipedia.org/wiki/Pointer_(computer_programming)">pointers</a></em>,
|
||||
allowing you to pass references to values and records
|
||||
within your program.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>We’ll show how pointers work in contrast to values with
|
||||
2 functions: <code>zeroval</code> and <code>zeroptr</code>. <code>zeroval</code> has an
|
||||
<code>int</code> parameter, so arguments will be passed to it by
|
||||
value. <code>zeroval</code> will get a copy of <code>ival</code> distinct
|
||||
from the one in the calling function.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">zeroval</span><span class="p">(</span><span class="nx">ival</span> <span class="kt">int</span><span class="p">)</span> <span class="p">{</span>
|
||||
<span class="nx">ival</span> <span class="p">=</span> <span class="mi">0</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p><code>zeroptr</code> in contrast has an <code>*int</code> parameter, meaning
|
||||
that it takes an <code>int</code> pointer. The <code>*iptr</code> code in the
|
||||
function body then <em>dereferences</em> the pointer from its
|
||||
memory address to the current value at that address.
|
||||
Assigning a value to a dereferenced pointer changes the
|
||||
value at the referenced address.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">zeroptr</span><span class="p">(</span><span class="nx">iptr</span> <span class="o">*</span><span class="kt">int</span><span class="p">)</span> <span class="p">{</span>
|
||||
<span class="o">*</span><span class="nx">iptr</span> <span class="p">=</span> <span class="mi">0</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
<span class="nx">i</span> <span class="o">:=</span> <span class="mi">1</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"initial:"</span><span class="p">,</span> <span class="nx">i</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">zeroval</span><span class="p">(</span><span class="nx">i</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"zeroval:"</span><span class="p">,</span> <span class="nx">i</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>The <code>&i</code> syntax gives the memory address of <code>i</code>,
|
||||
i.e. a pointer to <code>i</code>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">zeroptr</span><span class="p">(</span><span class="o">&</span><span class="nx">i</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"zeroptr:"</span><span class="p">,</span> <span class="nx">i</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Pointers can be printed too.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"pointer:"</span><span class="p">,</span> <span class="o">&</span><span class="nx">i</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p><code>zeroval</code> doesn’t change the <code>i</code> in <code>main</code>, but
|
||||
<code>zeroptr</code> does because it has a reference to
|
||||
the memory address for that variable.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run pointers.go
|
||||
<span class="go">initial: 1</span>
|
||||
<span class="go">zeroval: 1</span>
|
||||
<span class="go">zeroptr: 0</span>
|
||||
<span class="go">pointer: 0x42131100</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="structs">Structs</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/pointers">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
206
public/random-numbers
Normal file
206
public/random-numbers
Normal file
@ -0,0 +1,206 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Random Numbers</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="random-numbers">
|
||||
<h2><a href="./">Go by Example</a>: Random Numbers</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Go’s <code>math/rand</code> package provides
|
||||
<a href="http://en.wikipedia.org/wiki/Pseudorandom_number_generator">pseudorandom number</a>
|
||||
generation.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
<span class="kn">import</span> <span class="s">"math/rand"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>For example, <code>rand.Intn</code> returns a random <code>int</code> n,
|
||||
<code>0 <= n < 100</code>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Print</span><span class="p">(</span><span class="nx">rand</span><span class="p">.</span><span class="nx">Intn</span><span class="p">(</span><span class="mi">100</span><span class="p">),</span> <span class="s">","</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Print</span><span class="p">(</span><span class="nx">rand</span><span class="p">.</span><span class="nx">Intn</span><span class="p">(</span><span class="mi">100</span><span class="p">))</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">()</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p><code>rand.Float64</code> returns a <code>float64</code> <code>f</code>,
|
||||
<code>0.0 <= f < 1.0</code>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">rand</span><span class="p">.</span><span class="nx">Float64</span><span class="p">())</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>This can be used to generate random floats in
|
||||
other ranges, for example <code>5.0 <= f' < 10.0</code>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Print</span><span class="p">((</span><span class="nx">rand</span><span class="p">.</span><span class="nx">Float64</span><span class="p">()</span><span class="o">*</span><span class="mi">5</span><span class="p">)</span><span class="o">+</span><span class="mi">5</span><span class="p">,</span> <span class="s">","</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Print</span><span class="p">((</span><span class="nx">rand</span><span class="p">.</span><span class="nx">Float64</span><span class="p">()</span> <span class="o">*</span> <span class="mi">5</span><span class="p">)</span> <span class="o">+</span> <span class="mi">5</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">()</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>To make the pseudorandom generator deterministic,
|
||||
give it a well-known seed.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">s1</span> <span class="o">:=</span> <span class="nx">rand</span><span class="p">.</span><span class="nx">NewSource</span><span class="p">(</span><span class="mi">42</span><span class="p">)</span>
|
||||
<span class="nx">r1</span> <span class="o">:=</span> <span class="nx">rand</span><span class="p">.</span><span class="nx">New</span><span class="p">(</span><span class="nx">s1</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Call the resulting <code>rand.Source</code> just like the
|
||||
functions on the <code>rand</code> package.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Print</span><span class="p">(</span><span class="nx">r1</span><span class="p">.</span><span class="nx">Intn</span><span class="p">(</span><span class="mi">100</span><span class="p">),</span> <span class="s">","</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Print</span><span class="p">(</span><span class="nx">r1</span><span class="p">.</span><span class="nx">Intn</span><span class="p">(</span><span class="mi">100</span><span class="p">))</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">()</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>If you seed a source with the same number, it
|
||||
produces the same sequence of random numbers.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre> <span class="nx">s2</span> <span class="o">:=</span> <span class="nx">rand</span><span class="p">.</span><span class="nx">NewSource</span><span class="p">(</span><span class="mi">42</span><span class="p">)</span>
|
||||
<span class="nx">r2</span> <span class="o">:=</span> <span class="nx">rand</span><span class="p">.</span><span class="nx">New</span><span class="p">(</span><span class="nx">s2</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Print</span><span class="p">(</span><span class="nx">r2</span><span class="p">.</span><span class="nx">Intn</span><span class="p">(</span><span class="mi">100</span><span class="p">),</span> <span class="s">","</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Print</span><span class="p">(</span><span class="nx">r2</span><span class="p">.</span><span class="nx">Intn</span><span class="p">(</span><span class="mi">100</span><span class="p">))</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">()</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run random-numbers.go
|
||||
<span class="go">81,87</span>
|
||||
<span class="go">0.6645600532184904</span>
|
||||
<span class="go">7.123187485356329,8.434115364335547</span>
|
||||
<span class="go">5,87</span>
|
||||
<span class="go">5,87</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>See the <a href="http://golang.org/pkg/math/rand/"><code>math/rand</code></a>
|
||||
package docs for references on other random quantities
|
||||
that Go can provide.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="number-parsing">Number Parsing</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/random-numbers">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
174
public/range
Normal file
174
public/range
Normal file
@ -0,0 +1,174 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Range</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
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var _gaq = _gaq || [];
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_gaq.push(['_setAccount', 'UA-34996217-1']);
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|
||||
<body>
|
||||
<div class="example" id="range">
|
||||
<h2><a href="./">Go by Example</a>: Range</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p><em>range</em> iterates over of elements in a variety of
|
||||
data structures. Let’s see how to use <code>range</code> with some
|
||||
of the data structures we’ve already learned.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Here we use <code>range</code> to sum the numbers in a slice.
|
||||
Arrays work like this too.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">nums</span> <span class="o">:=</span> <span class="p">[]</span><span class="kt">int</span><span class="p">{</span><span class="mi">2</span><span class="p">,</span> <span class="mi">3</span><span class="p">,</span> <span class="mi">4</span><span class="p">}</span>
|
||||
<span class="nx">sum</span> <span class="o">:=</span> <span class="mi">0</span>
|
||||
<span class="k">for</span> <span class="nx">_</span><span class="p">,</span> <span class="nx">num</span> <span class="o">:=</span> <span class="k">range</span> <span class="nx">nums</span> <span class="p">{</span>
|
||||
<span class="nx">sum</span> <span class="o">+=</span> <span class="nx">num</span>
|
||||
<span class="p">}</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"sum:"</span><span class="p">,</span> <span class="nx">sum</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p><code>range</code> on arrays and slices provides both the
|
||||
index and value for each entry. Above we didn’t
|
||||
need the index, so we ignored it with the
|
||||
<em>blank identifier</em> <code>_</code>. Sometimes we actually want
|
||||
the indexes though.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="k">for</span> <span class="nx">i</span><span class="p">,</span> <span class="nx">num</span> <span class="o">:=</span> <span class="k">range</span> <span class="nx">nums</span> <span class="p">{</span>
|
||||
<span class="k">if</span> <span class="nx">num</span> <span class="o">==</span> <span class="mi">3</span> <span class="p">{</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"index:"</span><span class="p">,</span> <span class="nx">i</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p><code>range</code> on map iterates over key/value pairs.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">kvs</span> <span class="o">:=</span> <span class="kd">map</span><span class="p">[</span><span class="kt">string</span><span class="p">]</span><span class="kt">string</span><span class="p">{</span><span class="s">"a"</span><span class="p">:</span> <span class="s">"apple"</span><span class="p">,</span> <span class="s">"b"</span><span class="p">:</span> <span class="s">"bannana"</span><span class="p">}</span>
|
||||
<span class="k">for</span> <span class="nx">k</span><span class="p">,</span> <span class="nx">v</span> <span class="o">:=</span> <span class="k">range</span> <span class="nx">kvs</span> <span class="p">{</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Printf</span><span class="p">(</span><span class="s">"%s -> %s\n"</span><span class="p">,</span> <span class="nx">k</span><span class="p">,</span> <span class="nx">v</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p><code>range</code> on strings iterates over Unicode code
|
||||
points. The first value is the starting byte index
|
||||
of the <code>rune</code> and the second the <code>rune</code> itself.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre> <span class="k">for</span> <span class="nx">i</span><span class="p">,</span> <span class="nx">c</span> <span class="o">:=</span> <span class="k">range</span> <span class="s">"go"</span> <span class="p">{</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">i</span><span class="p">,</span> <span class="nx">c</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run range.go
|
||||
<span class="go">sum: 9</span>
|
||||
<span class="go">index: 1</span>
|
||||
<span class="go">a -> apple</span>
|
||||
<span class="go">b -> bannana</span>
|
||||
<span class="go">0 103</span>
|
||||
<span class="go">1 111</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="functions">Functions</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/range">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
147
public/range-over-channels
Normal file
147
public/range-over-channels
Normal file
@ -0,0 +1,147 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Range over Channels</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
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_gaq.push(['_setAccount', 'UA-34996217-1']);
|
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_gaq.push(['_trackPageview']);
|
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(function() {
|
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var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="range-over-channels">
|
||||
<h2><a href="./">Go by Example</a>: Range over Channels</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>In a <a href="range">previous</a> example we saw how <code>for</code> and
|
||||
<code>range</code> provide iteration over basic data structures.
|
||||
We can also use this syntax to iterate over
|
||||
values received from a channel.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>We’ll iterate over 2 values in the <code>queue</code> channel.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">queue</span> <span class="o">:=</span> <span class="nb">make</span><span class="p">(</span><span class="kd">chan</span> <span class="kt">string</span><span class="p">,</span> <span class="mi">2</span><span class="p">)</span>
|
||||
<span class="nx">queue</span> <span class="o"><-</span> <span class="s">"one"</span>
|
||||
<span class="nx">queue</span> <span class="o"><-</span> <span class="s">"two"</span>
|
||||
<span class="nb">close</span><span class="p">(</span><span class="nx">queue</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>This <code>range</code> iterates over each element as it’s
|
||||
received from <code>queue</code>. Because we <code>close</code>d the
|
||||
channel above, the iteration terminates after
|
||||
receiving the 2 elements. If we didn’t <code>close</code> it
|
||||
we’d block on a 3rd receive in the loop.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre> <span class="k">for</span> <span class="nx">elem</span> <span class="o">:=</span> <span class="k">range</span> <span class="nx">queue</span> <span class="p">{</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">elem</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run range-over-channels.go
|
||||
<span class="go">one</span>
|
||||
<span class="go">two</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>This example also showed that it’s possible to close
|
||||
a non-empty channel but still have the remaining
|
||||
values be received.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="timers">Timers</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/range-over-channels">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
246
public/rate-limiting
Normal file
246
public/rate-limiting
Normal file
@ -0,0 +1,246 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Rate Limiting</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="rate-limiting">
|
||||
<h2><a href="./">Go by Example</a>: Rate Limiting</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p><em><a href="http://en.wikipedia.org/wiki/Rate_limiting">Rate limiting</a></em>
|
||||
is an important mechanism for controlling resource
|
||||
utilization and maintaining quality of service. Go
|
||||
elegantly supports rate limiting with goroutines,
|
||||
channels, and <a href="tickers">tickers</a>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"time"</span>
|
||||
<span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>First we’ll look at basic rate limiting. Suppose
|
||||
we want to limit our handling of incoming requests.
|
||||
We’ll serve these requests off a channel of the
|
||||
same name.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">requests</span> <span class="o">:=</span> <span class="nb">make</span><span class="p">(</span><span class="kd">chan</span> <span class="kt">int</span><span class="p">,</span> <span class="mi">5</span><span class="p">)</span>
|
||||
<span class="k">for</span> <span class="nx">i</span> <span class="o">:=</span> <span class="mi">1</span><span class="p">;</span> <span class="nx">i</span> <span class="o"><=</span> <span class="mi">5</span><span class="p">;</span> <span class="nx">i</span><span class="o">++</span> <span class="p">{</span>
|
||||
<span class="nx">requests</span> <span class="o"><-</span> <span class="nx">i</span>
|
||||
<span class="p">}</span>
|
||||
<span class="nb">close</span><span class="p">(</span><span class="nx">requests</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>This <code>limiter</code> channel will receive a value
|
||||
every 200 milliseconds. This is the regulator in
|
||||
our rate limiting scheme.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">limiter</span> <span class="o">:=</span> <span class="nx">time</span><span class="p">.</span><span class="nx">Tick</span><span class="p">(</span><span class="nx">time</span><span class="p">.</span><span class="nx">Millisecond</span> <span class="o">*</span> <span class="mi">200</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>By blocking on a receive from the <code>limiter</code> channel
|
||||
before serving each request, we limit ourselves to
|
||||
1 request every 200 milliseconds.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="k">for</span> <span class="nx">req</span> <span class="o">:=</span> <span class="k">range</span> <span class="nx">requests</span> <span class="p">{</span>
|
||||
<span class="o"><-</span><span class="nx">limiter</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"request"</span><span class="p">,</span> <span class="nx">req</span><span class="p">,</span> <span class="nx">time</span><span class="p">.</span><span class="nx">Now</span><span class="p">())</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>We may want to allow short bursts of requests in
|
||||
our rate limiting scheme while preserving the
|
||||
overall rate limit. We can accomplish this by
|
||||
buffering our limiter channel. This <code>burstyLimiter</code>
|
||||
channel will allow bursts of up to 3 events.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">burstyLimiter</span> <span class="o">:=</span> <span class="nb">make</span><span class="p">(</span><span class="kd">chan</span> <span class="nx">time</span><span class="p">.</span><span class="nx">Time</span><span class="p">,</span> <span class="mi">3</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Fill up the channel to represent allowed bursting.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="k">for</span> <span class="nx">i</span> <span class="o">:=</span> <span class="mi">0</span><span class="p">;</span> <span class="nx">i</span> <span class="p"><</span> <span class="mi">3</span><span class="p">;</span> <span class="nx">i</span><span class="o">++</span> <span class="p">{</span>
|
||||
<span class="nx">burstyLimiter</span> <span class="o"><-</span> <span class="nx">time</span><span class="p">.</span><span class="nx">Now</span><span class="p">()</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Every 200 milliseconds we’ll try to add a new
|
||||
value to <code>burstyLimiter</code>, up to its limit of 3.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="k">go</span> <span class="kd">func</span><span class="p">()</span> <span class="p">{</span>
|
||||
<span class="k">for</span> <span class="nx">t</span> <span class="o">:=</span> <span class="k">range</span> <span class="nx">time</span><span class="p">.</span><span class="nx">Tick</span><span class="p">(</span><span class="nx">time</span><span class="p">.</span><span class="nx">Millisecond</span> <span class="o">*</span> <span class="mi">200</span><span class="p">)</span> <span class="p">{</span>
|
||||
<span class="nx">burstyLimiter</span> <span class="o"><-</span> <span class="nx">t</span>
|
||||
<span class="p">}</span>
|
||||
<span class="p">}()</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Now simulate 5 more incoming requests. The first
|
||||
3 of these will benefit from the burst capability
|
||||
of <code>burstyLimiter</code>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre> <span class="nx">burstyRequests</span> <span class="o">:=</span> <span class="nb">make</span><span class="p">(</span><span class="kd">chan</span> <span class="kt">int</span><span class="p">,</span> <span class="mi">5</span><span class="p">)</span>
|
||||
<span class="k">for</span> <span class="nx">i</span> <span class="o">:=</span> <span class="mi">1</span><span class="p">;</span> <span class="nx">i</span> <span class="o"><=</span> <span class="mi">5</span><span class="p">;</span> <span class="nx">i</span><span class="o">++</span> <span class="p">{</span>
|
||||
<span class="nx">burstyRequests</span> <span class="o"><-</span> <span class="nx">i</span>
|
||||
<span class="p">}</span>
|
||||
<span class="nb">close</span><span class="p">(</span><span class="nx">burstyRequests</span><span class="p">)</span>
|
||||
<span class="k">for</span> <span class="nx">req</span> <span class="o">:=</span> <span class="k">range</span> <span class="nx">burstyRequests</span> <span class="p">{</span>
|
||||
<span class="o"><-</span><span class="nx">burstyLimiter</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"request"</span><span class="p">,</span> <span class="nx">req</span><span class="p">,</span> <span class="nx">time</span><span class="p">.</span><span class="nx">Now</span><span class="p">())</span>
|
||||
<span class="p">}</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Running our program we see the first batch of requests
|
||||
handled once every ~200 milliseconds as desired.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run rate-limiting.go
|
||||
<span class="go">request 1 2012-10-19 00:38:18.687438 +0000 UTC</span>
|
||||
<span class="go">request 2 2012-10-19 00:38:18.887471 +0000 UTC</span>
|
||||
<span class="go">request 3 2012-10-19 00:38:19.087238 +0000 UTC</span>
|
||||
<span class="go">request 4 2012-10-19 00:38:19.287338 +0000 UTC</span>
|
||||
<span class="go">request 5 2012-10-19 00:38:19.487331 +0000 UTC</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>For the second batch of requests we serve the first
|
||||
3 immediately because of the burstable rate limiting,
|
||||
then serve the remaining 2 with ~200ms delays each.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre><span class="go">request 1 2012-10-19 00:38:20.487578 +0000 UTC</span>
|
||||
<span class="go">request 2 2012-10-19 00:38:20.487645 +0000 UTC</span>
|
||||
<span class="go">request 3 2012-10-19 00:38:20.487676 +0000 UTC</span>
|
||||
<span class="go">request 4 2012-10-19 00:38:20.687483 +0000 UTC</span>
|
||||
<span class="go">request 5 2012-10-19 00:38:20.887542 +0000 UTC</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="atomic-counters">Atomic Counters</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/rate-limiting">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
280
public/reading-files
Normal file
280
public/reading-files
Normal file
@ -0,0 +1,280 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Reading Files</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="reading-files">
|
||||
<h2><a href="./">Go by Example</a>: Reading Files</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Reading and writing files are basic tasks needed for
|
||||
many Go programs. First we’ll look at some examples of
|
||||
reading files.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="p">(</span>
|
||||
<span class="s">"bufio"</span>
|
||||
<span class="s">"fmt"</span>
|
||||
<span class="s">"io"</span>
|
||||
<span class="s">"io/ioutil"</span>
|
||||
<span class="s">"os"</span>
|
||||
<span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Reading files requires checking most calls for errors.
|
||||
This helper will streamline our error checks below.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">check</span><span class="p">(</span><span class="nx">e</span> <span class="kt">error</span><span class="p">)</span> <span class="p">{</span>
|
||||
<span class="k">if</span> <span class="nx">e</span> <span class="o">!=</span> <span class="kc">nil</span> <span class="p">{</span>
|
||||
<span class="nb">panic</span><span class="p">(</span><span class="nx">e</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Perhaps the most basic file reading task is
|
||||
slurping a file’s entire contents into memory.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">dat</span><span class="p">,</span> <span class="nx">err</span> <span class="o">:=</span> <span class="nx">ioutil</span><span class="p">.</span><span class="nx">ReadFile</span><span class="p">(</span><span class="s">"/tmp/dat"</span><span class="p">)</span>
|
||||
<span class="nx">check</span><span class="p">(</span><span class="nx">err</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Print</span><span class="p">(</span><span class="nb">string</span><span class="p">(</span><span class="nx">dat</span><span class="p">))</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>You’ll often want more control over how and what
|
||||
parts of a file are read. For these tasks, start
|
||||
by <code>Open</code>ing a file to obtain an <code>os.File</code> value.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">f</span><span class="p">,</span> <span class="nx">err</span> <span class="o">:=</span> <span class="nx">os</span><span class="p">.</span><span class="nx">Open</span><span class="p">(</span><span class="s">"/tmp/dat"</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Read some bytes from the beginning of the file.
|
||||
Allow up to 5 to be read but also not how many
|
||||
actually were read.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">b1</span> <span class="o">:=</span> <span class="nb">make</span><span class="p">([]</span><span class="kt">byte</span><span class="p">,</span> <span class="mi">5</span><span class="p">)</span>
|
||||
<span class="nx">n1</span><span class="p">,</span> <span class="nx">err</span> <span class="o">:=</span> <span class="nx">f</span><span class="p">.</span><span class="nx">Read</span><span class="p">(</span><span class="nx">b1</span><span class="p">)</span>
|
||||
<span class="nx">check</span><span class="p">(</span><span class="nx">err</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Printf</span><span class="p">(</span><span class="s">"%d bytes: %s\n"</span><span class="p">,</span> <span class="nx">n1</span><span class="p">,</span> <span class="nb">string</span><span class="p">(</span><span class="nx">b1</span><span class="p">))</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>You can also <code>Seek</code> to a known location in the file
|
||||
and <code>Read</code> from there.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">o2</span><span class="p">,</span> <span class="nx">err</span> <span class="o">:=</span> <span class="nx">f</span><span class="p">.</span><span class="nx">Seek</span><span class="p">(</span><span class="mi">6</span><span class="p">,</span> <span class="mi">0</span><span class="p">)</span>
|
||||
<span class="nx">check</span><span class="p">(</span><span class="nx">err</span><span class="p">)</span>
|
||||
<span class="nx">b2</span> <span class="o">:=</span> <span class="nb">make</span><span class="p">([]</span><span class="kt">byte</span><span class="p">,</span> <span class="mi">2</span><span class="p">)</span>
|
||||
<span class="nx">n2</span><span class="p">,</span> <span class="nx">err</span> <span class="o">:=</span> <span class="nx">f</span><span class="p">.</span><span class="nx">Read</span><span class="p">(</span><span class="nx">b2</span><span class="p">)</span>
|
||||
<span class="nx">check</span><span class="p">(</span><span class="nx">err</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Printf</span><span class="p">(</span><span class="s">"%d bytes @ %d: %s\n"</span><span class="p">,</span> <span class="nx">n2</span><span class="p">,</span> <span class="nx">o2</span><span class="p">,</span> <span class="nb">string</span><span class="p">(</span><span class="nx">b2</span><span class="p">))</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>The <code>io</code> package provides some functions that may
|
||||
be helpful for file reading. For example, reads
|
||||
like the ones above can be more robustly
|
||||
implemented with <code>ReadAtLeast</code>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">o3</span><span class="p">,</span> <span class="nx">err</span> <span class="o">:=</span> <span class="nx">f</span><span class="p">.</span><span class="nx">Seek</span><span class="p">(</span><span class="mi">6</span><span class="p">,</span> <span class="mi">0</span><span class="p">)</span>
|
||||
<span class="nx">check</span><span class="p">(</span><span class="nx">err</span><span class="p">)</span>
|
||||
<span class="nx">b3</span> <span class="o">:=</span> <span class="nb">make</span><span class="p">([]</span><span class="kt">byte</span><span class="p">,</span> <span class="mi">2</span><span class="p">)</span>
|
||||
<span class="nx">n3</span><span class="p">,</span> <span class="nx">err</span> <span class="o">:=</span> <span class="nx">io</span><span class="p">.</span><span class="nx">ReadAtLeast</span><span class="p">(</span><span class="nx">f</span><span class="p">,</span> <span class="nx">b3</span><span class="p">,</span> <span class="mi">2</span><span class="p">)</span>
|
||||
<span class="nx">check</span><span class="p">(</span><span class="nx">err</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Printf</span><span class="p">(</span><span class="s">"%d bytes @ %d: %s\n"</span><span class="p">,</span> <span class="nx">n3</span><span class="p">,</span> <span class="nx">o3</span><span class="p">,</span> <span class="nb">string</span><span class="p">(</span><span class="nx">b3</span><span class="p">))</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>There is no built-in rewind, but <code>Seek(0, 0)</code>
|
||||
accomplishes this.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">_</span><span class="p">,</span> <span class="nx">err</span> <span class="p">=</span> <span class="nx">f</span><span class="p">.</span><span class="nx">Seek</span><span class="p">(</span><span class="mi">0</span><span class="p">,</span> <span class="mi">0</span><span class="p">)</span>
|
||||
<span class="nx">check</span><span class="p">(</span><span class="nx">err</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>The <code>bufio</code> package implements a buffered
|
||||
reader that may be useful both for it’s efficiency
|
||||
with many small reads and because of the additional
|
||||
reading methods it provides.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">r4</span> <span class="o">:=</span> <span class="nx">bufio</span><span class="p">.</span><span class="nx">NewReader</span><span class="p">(</span><span class="nx">f</span><span class="p">)</span>
|
||||
<span class="nx">b4</span><span class="p">,</span> <span class="nx">err</span> <span class="o">:=</span> <span class="nx">r4</span><span class="p">.</span><span class="nx">Peek</span><span class="p">(</span><span class="mi">5</span><span class="p">)</span>
|
||||
<span class="nx">check</span><span class="p">(</span><span class="nx">err</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Printf</span><span class="p">(</span><span class="s">"5 bytes: %s\n"</span><span class="p">,</span> <span class="nb">string</span><span class="p">(</span><span class="nx">b4</span><span class="p">))</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Close the file when you’re done (usually this would
|
||||
be scheduled immediately after <code>Open</code>ing with
|
||||
<code>defer</code>).</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">f</span><span class="p">.</span><span class="nx">Close</span><span class="p">()</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre><span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="gp">$</span> <span class="nb">echo</span> <span class="s2">"hello"</span> > /tmp/dat
|
||||
<span class="gp">$</span> <span class="nb">echo</span> <span class="s2">"go"</span> >> /tmp/dat
|
||||
<span class="gp">$</span> go run reading-files.go
|
||||
<span class="go">hello</span>
|
||||
<span class="go">go</span>
|
||||
<span class="go">5 bytes: hello</span>
|
||||
<span class="go">2 bytes @ 6: go</span>
|
||||
<span class="go">2 bytes @ 6: go</span>
|
||||
<span class="go">5 bytes: hello</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Next we’ll look at writing files.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="writing-files">Writing Files</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/reading-files">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
119
public/recursion
Normal file
119
public/recursion
Normal file
@ -0,0 +1,119 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Recursion</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="recursion">
|
||||
<h2><a href="./">Go by Example</a>: Recursion</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Go supports
|
||||
<a href="http://en.wikipedia.org/wiki/Recursion_(computer_science)"><em>recursive functions</em></a>.
|
||||
Here’s a classic factorial example.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>This <code>fact</code> function calls itself until it reaches the
|
||||
base case of <code>fact(0)</code>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">fact</span><span class="p">(</span><span class="nx">n</span> <span class="kt">int</span><span class="p">)</span> <span class="kt">int</span> <span class="p">{</span>
|
||||
<span class="k">if</span> <span class="nx">n</span> <span class="o">==</span> <span class="mi">0</span> <span class="p">{</span>
|
||||
<span class="k">return</span> <span class="mi">1</span>
|
||||
<span class="p">}</span>
|
||||
<span class="k">return</span> <span class="nx">n</span> <span class="o">*</span> <span class="nx">fact</span><span class="p">(</span><span class="nx">n</span><span class="o">-</span><span class="mi">1</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">fact</span><span class="p">(</span><span class="mi">7</span><span class="p">))</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run recursion.go
|
||||
<span class="go">5040</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="pointers">Pointers</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/recursion">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
320
public/regular-expressions
Normal file
320
public/regular-expressions
Normal file
@ -0,0 +1,320 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Regular Expressions</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="regular-expressions">
|
||||
<h2><a href="./">Go by Example</a>: Regular Expressions</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Go offers built-in support for <a href="http://en.wikipedia.org/wiki/Regular_expression">regular expressions</a>.
|
||||
Here are some examples of common regexp-related tasks
|
||||
in Go.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"bytes"</span>
|
||||
<span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
<span class="kn">import</span> <span class="s">"regexp"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>This tests whether a pattern matches a string.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">match</span><span class="p">,</span> <span class="nx">_</span> <span class="o">:=</span> <span class="nx">regexp</span><span class="p">.</span><span class="nx">MatchString</span><span class="p">(</span><span class="s">"p([a-z]+)ch"</span><span class="p">,</span> <span class="s">"peach"</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">match</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Above we used a string pattern directly, but for
|
||||
other regexp tasks you’ll need to <code>Compile</code> an
|
||||
optimized <code>Regexp</code> struct.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">r</span><span class="p">,</span> <span class="nx">_</span> <span class="o">:=</span> <span class="nx">regexp</span><span class="p">.</span><span class="nx">Compile</span><span class="p">(</span><span class="s">"p([a-z]+)ch"</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Many methods are available on these structs. Here’s
|
||||
a match test like we saw earlier.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">r</span><span class="p">.</span><span class="nx">MatchString</span><span class="p">(</span><span class="s">"peach"</span><span class="p">))</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>This finds the match for the regexp.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">r</span><span class="p">.</span><span class="nx">FindString</span><span class="p">(</span><span class="s">"peach punch"</span><span class="p">))</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>The also finds the first match but returns the
|
||||
start and end indexes for the match instead of the
|
||||
matching text.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">r</span><span class="p">.</span><span class="nx">FindStringIndex</span><span class="p">(</span><span class="s">"peach punch"</span><span class="p">))</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>The <code>Submatch</code> variants include information about
|
||||
both the whole-pattern matches and the submatches
|
||||
within those matches. For example this will return
|
||||
information for both <code>p([a-z]+)ch</code> and <code>([a-z]+)</code>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">r</span><span class="p">.</span><span class="nx">FindStringSubmatch</span><span class="p">(</span><span class="s">"peach punch"</span><span class="p">))</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Similarly this will return information about the
|
||||
indexes of matches and submatches.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">r</span><span class="p">.</span><span class="nx">FindStringSubmatchIndex</span><span class="p">(</span><span class="s">"peach punch"</span><span class="p">))</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>The <code>All</code> variants of these functions apply to all
|
||||
matches in the input, not just the first. For
|
||||
example to find all matches for a regexp.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">r</span><span class="p">.</span><span class="nx">FindAllString</span><span class="p">(</span><span class="s">"peach punch pinch"</span><span class="p">,</span> <span class="o">-</span><span class="mi">1</span><span class="p">))</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>These <code>All</code> variants are available for the other
|
||||
functions we saw above as well.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">r</span><span class="p">.</span><span class="nx">FindAllStringSubmatchIndex</span><span class="p">(</span>
|
||||
<span class="s">"peach punch pinch"</span><span class="p">,</span> <span class="o">-</span><span class="mi">1</span><span class="p">))</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Providing a non-negative integer as the second
|
||||
argument to these functions will limit the number
|
||||
of matches.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">r</span><span class="p">.</span><span class="nx">FindAllString</span><span class="p">(</span><span class="s">"peach punch pinch"</span><span class="p">,</span> <span class="mi">2</span><span class="p">))</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Our examples above had string arguments and used
|
||||
names like <code>MatchString</code>. We can also provide
|
||||
<code>[]byte</code> arguments and drop <code>String</code> from the
|
||||
function name.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">r</span><span class="p">.</span><span class="nx">Match</span><span class="p">([]</span><span class="nb">byte</span><span class="p">(</span><span class="s">"peach"</span><span class="p">)))</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>When creating constants with regular expressions
|
||||
you can use the <code>MustCompile</code> variation of
|
||||
<code>Compile</code>. A plain <code>Compile</code> won’t work for
|
||||
constants because it has 2 return values.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">r</span> <span class="p">=</span> <span class="nx">regexp</span><span class="p">.</span><span class="nx">MustCompile</span><span class="p">(</span><span class="s">"p([a-z]+)ch"</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">r</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>The <code>regexp</code> package can also be used to replace
|
||||
subsets of strings with other values.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">r</span><span class="p">.</span><span class="nx">ReplaceAllString</span><span class="p">(</span><span class="s">"a peach"</span><span class="p">,</span> <span class="s">"<fruit>"</span><span class="p">))</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>The <code>Func</code> variant allows you to transform matched
|
||||
text with a given function.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre> <span class="nx">in</span> <span class="o">:=</span> <span class="p">[]</span><span class="nb">byte</span><span class="p">(</span><span class="s">"a peach"</span><span class="p">)</span>
|
||||
<span class="nx">out</span> <span class="o">:=</span> <span class="nx">r</span><span class="p">.</span><span class="nx">ReplaceAllFunc</span><span class="p">(</span><span class="nx">in</span><span class="p">,</span> <span class="nx">bytes</span><span class="p">.</span><span class="nx">ToUpper</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nb">string</span><span class="p">(</span><span class="nx">out</span><span class="p">))</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run regular-expressions.go
|
||||
<span class="go">true</span>
|
||||
<span class="go">true</span>
|
||||
<span class="go">peach</span>
|
||||
<span class="go">[0 5]</span>
|
||||
<span class="go">[peach ea]</span>
|
||||
<span class="go">[0 5 1 3]</span>
|
||||
<span class="go">[peach punch pinch]</span>
|
||||
<span class="go">[[0 5 1 3] [6 11 7 9] [12 17 13 15]]</span>
|
||||
<span class="go">[peach punch]</span>
|
||||
<span class="go">true</span>
|
||||
<span class="go">p([a-z]+)ch</span>
|
||||
<span class="go">a <fruit></span>
|
||||
<span class="go">a PEACH</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>For a complete reference on Go regular expressions check
|
||||
the <a href="http://golang.org/pkg/regexp/"><code>regexp</code></a> package docs.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="json">JSON</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/regular-expressions">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
172
public/select
Normal file
172
public/select
Normal file
@ -0,0 +1,172 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Select</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="select">
|
||||
<h2><a href="./">Go by Example</a>: Select</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Go’s <em>select</em> lets you wait on multiple channel
|
||||
operations. Combining goroutines and channels with
|
||||
select is powerful feature of Go.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"time"</span>
|
||||
<span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>For our example we’ll select across two channels.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">c1</span> <span class="o">:=</span> <span class="nb">make</span><span class="p">(</span><span class="kd">chan</span> <span class="kt">string</span><span class="p">)</span>
|
||||
<span class="nx">c2</span> <span class="o">:=</span> <span class="nb">make</span><span class="p">(</span><span class="kd">chan</span> <span class="kt">string</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Each channel will receive a value after some amount
|
||||
of time, to simulate e.g. blocking RPC operations
|
||||
executing in concurrent goroutines.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="k">go</span> <span class="kd">func</span><span class="p">()</span> <span class="p">{</span>
|
||||
<span class="nx">time</span><span class="p">.</span><span class="nx">Sleep</span><span class="p">(</span><span class="nx">time</span><span class="p">.</span><span class="nx">Second</span> <span class="o">*</span> <span class="mi">1</span><span class="p">)</span>
|
||||
<span class="nx">c1</span> <span class="o"><-</span> <span class="s">"one"</span>
|
||||
<span class="p">}()</span>
|
||||
<span class="k">go</span> <span class="kd">func</span><span class="p">()</span> <span class="p">{</span>
|
||||
<span class="nx">time</span><span class="p">.</span><span class="nx">Sleep</span><span class="p">(</span><span class="nx">time</span><span class="p">.</span><span class="nx">Second</span> <span class="o">*</span> <span class="mi">2</span><span class="p">)</span>
|
||||
<span class="nx">c2</span> <span class="o"><-</span> <span class="s">"two"</span>
|
||||
<span class="p">}()</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>We’ll use <code>select</code> to await both of these values
|
||||
simultaneously, printing each one as it arrives.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre> <span class="k">for</span> <span class="nx">i</span> <span class="o">:=</span> <span class="mi">0</span><span class="p">;</span> <span class="nx">i</span> <span class="p"><</span> <span class="mi">2</span><span class="p">;</span> <span class="nx">i</span><span class="o">++</span> <span class="p">{</span>
|
||||
<span class="k">select</span> <span class="p">{</span>
|
||||
<span class="k">case</span> <span class="nx">msg1</span> <span class="o">:=</span> <span class="o"><-</span><span class="nx">c1</span><span class="p">:</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"received"</span><span class="p">,</span> <span class="nx">msg1</span><span class="p">)</span>
|
||||
<span class="k">case</span> <span class="nx">msg2</span> <span class="o">:=</span> <span class="o"><-</span><span class="nx">c2</span><span class="p">:</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"received"</span><span class="p">,</span> <span class="nx">msg2</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
<span class="p">}</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>We receive the values <code>"one"</code> and then <code>"two"</code> as
|
||||
expected.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="gp">$</span> <span class="nb">time </span>go run <span class="k">select</span>.go
|
||||
<span class="go">received one</span>
|
||||
<span class="go">received two</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Note that the total execution time is only ~2 seconds
|
||||
since both the 1 and 2 second <code>Sleeps</code> execute
|
||||
concurrently.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre><span class="go">real 0m2.245s</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="timeouts">Timeouts</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/select">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
190
public/sha1-hashes
Normal file
190
public/sha1-hashes
Normal file
@ -0,0 +1,190 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: SHA1 Hashes</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="sha1-hashes">
|
||||
<h2><a href="./">Go by Example</a>: SHA1 Hashes</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p><a href="http://en.wikipedia.org/wiki/SHA-1"><em>SHA1 hashes</em></a> are
|
||||
frequently used to compute short identities for binary
|
||||
or text blobs. For example, the <a href="http://git-scm.com/">git revision control
|
||||
system</a> uses SHA1s extensively to
|
||||
identify versioned files and directories. Here’s how to
|
||||
compute SHA1 hashes in Go.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Go implements several hash functions in various
|
||||
<code>crypto/*</code> packages.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"crypto/sha1"</span>
|
||||
<span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
<span class="nx">s</span> <span class="o">:=</span> <span class="s">"sha1 this string"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>The pattern for generating a hash is <code>sha1.New()</code>,
|
||||
<code>sha1.Write(bytes)</code>, then <code>sha1.Sum([]byte{})</code>.
|
||||
Here we start with a new hash.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">h</span> <span class="o">:=</span> <span class="nx">sha1</span><span class="p">.</span><span class="nx">New</span><span class="p">()</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p><code>Write</code> expects bytes. If you have a string <code>s</code>,
|
||||
use <code>[]byte(s)</code> to coerce it to bytes.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">h</span><span class="p">.</span><span class="nx">Write</span><span class="p">([]</span><span class="nb">byte</span><span class="p">(</span><span class="nx">s</span><span class="p">))</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>This gets the finalized hash result as a byte
|
||||
slice. The argument to <code>Sum</code> can be used to append
|
||||
to an existing byte slice: it usually isn’t needed.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">bs</span> <span class="o">:=</span> <span class="nx">h</span><span class="p">.</span><span class="nx">Sum</span><span class="p">(</span><span class="kc">nil</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>SHA1 values are often printed in hex, for example
|
||||
in git commits. Use the <code>%x</code> format verb to convert
|
||||
a hash results to a hex string.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">s</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Printf</span><span class="p">(</span><span class="s">"%x\n"</span><span class="p">,</span> <span class="nx">bs</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Running the program computes the hash and prints it in
|
||||
a human-readable hex format.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run sha1-hashes.go
|
||||
<span class="go">sha1 this string</span>
|
||||
<span class="go">cf23df2207d99a74fbe169e3eba035e633b65d94</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>You can compute other hashes using a similar pattern to
|
||||
the one shown above. For example, to compute MD5 hashes
|
||||
import <code>crypto/md5</code> and use <code>md5.New()</code>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Note that if you need cryptographically secure hashes,
|
||||
you should carefully research
|
||||
<a href="http://en.wikipedia.org/wiki/Cryptographic_hash_function">hash strength</a>!</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="base64-encoding">Base64 Encoding</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/sha1-hashes">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
177
public/signals
Normal file
177
public/signals
Normal file
@ -0,0 +1,177 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Signals</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="signals">
|
||||
<h2><a href="./">Go by Example</a>: Signals</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Sometines we’d like our Go programs to intelligently
|
||||
handle <a href="http://en.wikipedia.org/wiki/Unix_signal">Unix signals</a>.
|
||||
For example, we might want a server to gracefully
|
||||
shutdown when it receives a <code>SIGTERM</code>, or a command-line
|
||||
tool to stop processing input if it receives a <code>SIGINT</code>.
|
||||
Here’s how to handle signals in Go with channels.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
<span class="kn">import</span> <span class="s">"os"</span>
|
||||
<span class="kn">import</span> <span class="s">"os/signal"</span>
|
||||
<span class="kn">import</span> <span class="s">"syscall"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Go signal notification works by sending <code>os.Signal</code>
|
||||
values on a channel. We’ll create a channel to
|
||||
receive these notifications (we’ll also make one to
|
||||
notify us when the program can exit.)</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">sigs</span> <span class="o">:=</span> <span class="nb">make</span><span class="p">(</span><span class="kd">chan</span> <span class="nx">os</span><span class="p">.</span><span class="nx">Signal</span><span class="p">,</span> <span class="mi">1</span><span class="p">)</span>
|
||||
<span class="nx">done</span> <span class="o">:=</span> <span class="nb">make</span><span class="p">(</span><span class="kd">chan</span> <span class="kt">bool</span><span class="p">,</span> <span class="mi">1</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p><code>signal.Notify</code> registers the given channel to
|
||||
receive notifications of the specified signals.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">signal</span><span class="p">.</span><span class="nx">Notify</span><span class="p">(</span><span class="nx">sigs</span><span class="p">,</span> <span class="nx">syscall</span><span class="p">.</span><span class="nx">SIGINT</span><span class="p">,</span> <span class="nx">syscall</span><span class="p">.</span><span class="nx">SIGTERM</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>This goroutine executes a blocking receive for
|
||||
signals. When it gets one it’ll print it out
|
||||
and then notify the program that it can finish.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="k">go</span> <span class="kd">func</span><span class="p">()</span> <span class="p">{</span>
|
||||
<span class="nx">sig</span> <span class="o">:=</span> <span class="o"><-</span><span class="nx">sigs</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">()</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">sig</span><span class="p">)</span>
|
||||
<span class="nx">done</span> <span class="o"><-</span> <span class="kc">true</span>
|
||||
<span class="p">}()</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>The program will wait here until it gets the
|
||||
expected signal (as indicated by the goroutine
|
||||
above sending a value on <code>done</code>) and then exit.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"awaiting signal"</span><span class="p">)</span>
|
||||
<span class="o"><-</span><span class="nx">done</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"exiting"</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>When we run this program it will block waiting for a
|
||||
signal. By typing <code>ctrl-C</code> (which the
|
||||
terminal shows as <code>^C</code>) we can send a <code>SIGINT</code> signal,
|
||||
causing the program to print <code>interrupt</code> and then exit.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run signals.go
|
||||
<span class="go">awaiting signal</span>
|
||||
<span class="go">^C</span>
|
||||
<span class="go">interrupt</span>
|
||||
<span class="go">exiting</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="exit">Exit</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/signals">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
201
public/site.css
Normal file
201
public/site.css
Normal file
@ -0,0 +1,201 @@
|
||||
/* CSS reset: http://meyerweb.com/eric/tools/css/reset/ */
|
||||
html, body, div, span, applet, object, iframe,
|
||||
h1, h2, h3, h4, h5, h6, p, blockquote, pre,
|
||||
a, abbr, acronym, address, big, cite, code,
|
||||
del, dfn, em, img, ins, kbd, q, s, samp,
|
||||
small, strike, strong, sub, sup, tt, var,
|
||||
b, u, i, center,
|
||||
dl, dt, dd, ol, ul, li,
|
||||
fieldset, form, label, legend,
|
||||
table, caption, tbody, tfoot, thead, tr, th, td,
|
||||
article, aside, canvas, details, embed,
|
||||
figure, figcaption, footer, header, hgroup,
|
||||
menu, nav, output, ruby, section, summary,
|
||||
time, mark, audio, video {
|
||||
margin: 0;
|
||||
padding: 0;
|
||||
border: 0;
|
||||
font-size: 100%;
|
||||
font: inherit;
|
||||
vertical-align: baseline;
|
||||
}
|
||||
article, aside, details, figcaption, figure,
|
||||
footer, header, hgroup, menu, nav, section {
|
||||
display: block;
|
||||
}
|
||||
body {
|
||||
line-height: 1;
|
||||
}
|
||||
ol, ul {
|
||||
list-style: none;
|
||||
}
|
||||
blockquote, q {
|
||||
quotes: none;
|
||||
}
|
||||
blockquote:before, blockquote:after,
|
||||
q:before, q:after {
|
||||
content: '';
|
||||
content: none;
|
||||
}
|
||||
table {
|
||||
border-collapse: collapse;
|
||||
border-spacing: 0;
|
||||
}
|
||||
|
||||
/* Layout and typography */
|
||||
body {
|
||||
font-family: 'Georgia', serif;
|
||||
font-size: 16px;
|
||||
line-height: 20px;
|
||||
color: #252519;
|
||||
}
|
||||
em {
|
||||
font-style: italic;
|
||||
}
|
||||
a, a:visited {
|
||||
color: #261a3b;
|
||||
}
|
||||
h2 {
|
||||
font-size: 32px;
|
||||
line-height: 40px;
|
||||
margin-top: 40px;
|
||||
}
|
||||
h2 a {
|
||||
text-decoration: none;
|
||||
}
|
||||
div.example {
|
||||
width: 900px;
|
||||
min-width: 900px;
|
||||
max-width: 900px;
|
||||
margin-left: auto;
|
||||
margin-right: auto;
|
||||
margin-bottom: 120px;
|
||||
}
|
||||
div.example table {
|
||||
margin-top: 15px;
|
||||
margin-bottom: 20px;
|
||||
}
|
||||
p.next {
|
||||
margin-bottom: 20px;
|
||||
}
|
||||
p.footer {
|
||||
color: grey;
|
||||
}
|
||||
p.footer a, p.footer a:visited {
|
||||
color: grey;
|
||||
}
|
||||
div#intro {
|
||||
width: 420px;
|
||||
min-width: 420px;
|
||||
max-width: 420px;
|
||||
margin-left: auto;
|
||||
margin-right: auto;
|
||||
margin-bottom: 120px;
|
||||
}
|
||||
div#intro p {
|
||||
padding-top: 20px;
|
||||
}
|
||||
div#intro ul {
|
||||
padding-top: 20px;
|
||||
}
|
||||
table td {
|
||||
border: 0;
|
||||
outline: 0;
|
||||
}
|
||||
td.docs {
|
||||
width: 420px;
|
||||
max-width: 420px;
|
||||
min-width: 420px;
|
||||
min-height: 5px;
|
||||
vertical-align: top;
|
||||
text-align: left;
|
||||
}
|
||||
td.docs p {
|
||||
padding-right: 5px;
|
||||
padding-top: 5px;
|
||||
padding-bottom: 15px;
|
||||
}
|
||||
td.code {
|
||||
width: 480px;
|
||||
max-width: 480px;
|
||||
min-width: 480px;
|
||||
padding-top: 5px;
|
||||
padding-right: 5px;
|
||||
padding-left: 5px;
|
||||
padding-bottom: 5px;
|
||||
vertical-align: top;
|
||||
background: #f0f0f0;
|
||||
}
|
||||
td.code.leading {
|
||||
padding-bottom: 11px;
|
||||
}
|
||||
td.code.empty {
|
||||
background: #ffffff;
|
||||
}
|
||||
pre, code {
|
||||
font-size: 14px; line-height: 18px;
|
||||
font-family: 'Menlo', 'Monaco', 'Consolas', 'Lucida Console', monospace;
|
||||
}
|
||||
|
||||
/* Syntax highlighting */
|
||||
body .hll { background-color: #ffffcc }
|
||||
body .err { border: 1px solid #FF0000 } /* Error */
|
||||
body .c { color: #408080; font-style: italic } /* Comment */
|
||||
body .k { color: #954121 } /* Keyword */
|
||||
body .o { color: #666666 } /* Operator */
|
||||
body .cm { color: #408080; font-style: italic } /* Comment.Multiline */
|
||||
body .cp { color: #BC7A00 } /* Comment.Preproc */
|
||||
body .c1 { color: #408080; font-style: italic } /* Comment.Single */
|
||||
body .cs { color: #408080; font-style: italic } /* Comment.Special */
|
||||
body .gd { color: #A00000 } /* Generic.Deleted */
|
||||
body .ge { font-style: italic } /* Generic.Emph */
|
||||
body .gr { color: #FF0000 } /* Generic.Error */
|
||||
body .gh { color: #000080; font-weight: bold } /* Generic.Heading */
|
||||
body .gi { color: #00A000 } /* Generic.Inserted */
|
||||
body .go { color: #808080 } /* Generic.Output */
|
||||
body .gp { color: #000080; font-weight: bold } /* Generic.Prompt */
|
||||
body .gs { font-weight: bold } /* Generic.Strong */
|
||||
body .gu { color: #800080; font-weight: bold } /* Generic.Subheading */
|
||||
body .gt { color: #0040D0 } /* Generic.Traceback */
|
||||
body .kc { color: #954121 } /* Keyword.Constant */
|
||||
body .kd { color: #954121 } /* Keyword.Declaration */
|
||||
body .kn { color: #954121 } /* Keyword.Namespace */
|
||||
body .kp { color: #954121 } /* Keyword.Pseudo */
|
||||
body .kr { color: #954121; font-weight: bold } /* Keyword.Reserved */
|
||||
body .kt { color: #B00040 } /* Keyword.Type */
|
||||
body .m { color: #666666 } /* Literal.Number */
|
||||
body .s { color: #219161 } /* Literal.String */
|
||||
body .na { color: #7D9029 } /* Name.Attribute */
|
||||
body .nb { color: #954121 } /* Name.Builtin */
|
||||
body .nc { color: #0000FF; font-weight: bold } /* Name.Class */
|
||||
body .no { color: #880000 } /* Name.Constant */
|
||||
body .nd { color: #AA22FF } /* Name.Decorator */
|
||||
body .ni { color: #999999; font-weight: bold } /* Name.Entity */
|
||||
body .ne { color: #D2413A; font-weight: bold } /* Name.Exception */
|
||||
body .nf { color: #0000FF } /* Name.Function */
|
||||
body .nl { color: #A0A000 } /* Name.Label */
|
||||
body .nn { color: #0000FF; font-weight: bold } /* Name.Namespace */
|
||||
body .nt { color: #954121; font-weight: bold } /* Name.Tag */
|
||||
body .nv { color: #19469D } /* Name.Variable */
|
||||
body .ow { color: #AA22FF; font-weight: bold } /* Operator.Word */
|
||||
body .w { color: #bbbbbb } /* Text.Whitespace */
|
||||
body .mf { color: #666666 } /* Literal.Number.Float */
|
||||
body .mh { color: #666666 } /* Literal.Number.Hex */
|
||||
body .mi { color: #666666 } /* Literal.Number.Integer */
|
||||
body .mo { color: #666666 } /* Literal.Number.Oct */
|
||||
body .sb { color: #219161 } /* Literal.String.Backtick */
|
||||
body .sc { color: #219161 } /* Literal.String.Char */
|
||||
body .sd { color: #219161; font-style: italic } /* Literal.String.Doc */
|
||||
body .s2 { color: #219161 } /* Literal.String.Double */
|
||||
body .se { color: #BB6622; font-weight: bold } /* Literal.String.Escape */
|
||||
body .sh { color: #219161 } /* Literal.String.Heredoc */
|
||||
body .si { color: #BB6688; font-weight: bold } /* Literal.String.Interpol */
|
||||
body .sx { color: #954121 } /* Literal.String.Other */
|
||||
body .sr { color: #BB6688 } /* Literal.String.Regex */
|
||||
body .s1 { color: #219161 } /* Literal.String.Single */
|
||||
body .ss { color: #19469D } /* Literal.String.Symbol */
|
||||
body .bp { color: #954121 } /* Name.Builtin.Pseudo */
|
||||
body .vc { color: #19469D } /* Name.Variable.Class */
|
||||
body .vg { color: #19469D } /* Name.Variable.Global */
|
||||
body .vi { color: #19469D } /* Name.Variable.Instance */
|
||||
body .il { color: #666666 } /* Literal.Number.Integer.Long */
|
||||
291
public/slices
Normal file
291
public/slices
Normal file
@ -0,0 +1,291 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Slices</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="slices">
|
||||
<h2><a href="./">Go by Example</a>: Slices</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p><em>Slices</em> are a key data type in Go, giving a more
|
||||
powerful interface to sequences than arrays.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Unlike arrays, slices are typed only by the
|
||||
elements they contain (not the number of elements).
|
||||
To create an empty slice with non-zero length, use
|
||||
the builtin <code>make</code>. Here we make a slice of
|
||||
<code>string</code>s of length <code>3</code> (initially zero-valued).</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">s</span> <span class="o">:=</span> <span class="nb">make</span><span class="p">([]</span><span class="kt">string</span><span class="p">,</span> <span class="mi">3</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"emp:"</span><span class="p">,</span> <span class="nx">s</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>We can set and get just like with arrays.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">s</span><span class="p">[</span><span class="mi">0</span><span class="p">]</span> <span class="p">=</span> <span class="s">"a"</span>
|
||||
<span class="nx">s</span><span class="p">[</span><span class="mi">1</span><span class="p">]</span> <span class="p">=</span> <span class="s">"b"</span>
|
||||
<span class="nx">s</span><span class="p">[</span><span class="mi">2</span><span class="p">]</span> <span class="p">=</span> <span class="s">"c"</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"set:"</span><span class="p">,</span> <span class="nx">s</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"get:"</span><span class="p">,</span> <span class="nx">s</span><span class="p">[</span><span class="mi">2</span><span class="p">])</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p><code>len</code> returns the length of the slice as expected.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"len:"</span><span class="p">,</span> <span class="nb">len</span><span class="p">(</span><span class="nx">s</span><span class="p">))</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>In addition to these basic operations, slices
|
||||
support several more that make them richer than
|
||||
arrays. One is the builtin <code>append</code>, which
|
||||
returns a slice containing one or more new values.
|
||||
Note that we need to accept a return value from
|
||||
append as we may get a new slice value.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">s</span> <span class="p">=</span> <span class="nb">append</span><span class="p">(</span><span class="nx">s</span><span class="p">,</span> <span class="s">"d"</span><span class="p">)</span>
|
||||
<span class="nx">s</span> <span class="p">=</span> <span class="nb">append</span><span class="p">(</span><span class="nx">s</span><span class="p">,</span> <span class="s">"e"</span><span class="p">,</span> <span class="s">"f"</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"apd:"</span><span class="p">,</span> <span class="nx">s</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Slices can also be <code>copy</code>’d. Here we create an
|
||||
empty slice <code>c</code> of the same length as <code>s</code> and copy
|
||||
into <code>c</code> from <code>s</code>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">c</span> <span class="o">:=</span> <span class="nb">make</span><span class="p">([]</span><span class="kt">string</span><span class="p">,</span> <span class="nb">len</span><span class="p">(</span><span class="nx">s</span><span class="p">))</span>
|
||||
<span class="nb">copy</span><span class="p">(</span><span class="nx">c</span><span class="p">,</span> <span class="nx">s</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"cpy:"</span><span class="p">,</span> <span class="nx">c</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Slices support a “slice” operator with the syntax
|
||||
<code>slice[low:high]</code>. For example, this gets a slice
|
||||
of the elements <code>s[2]</code>, <code>s[3]</code>, and <code>s[4]</code>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">l</span> <span class="o">:=</span> <span class="nx">s</span><span class="p">[</span><span class="mi">2</span><span class="p">:</span><span class="mi">5</span><span class="p">]</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"sl1:"</span><span class="p">,</span> <span class="nx">l</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>This slices up to (but excluding) <code>s[5]</code>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">l</span> <span class="p">=</span> <span class="nx">s</span><span class="p">[:</span><span class="mi">5</span><span class="p">]</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"sl2:"</span><span class="p">,</span> <span class="nx">l</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>And this slices up from (and including) <code>s[2]</code>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">l</span> <span class="p">=</span> <span class="nx">s</span><span class="p">[</span><span class="mi">2</span><span class="p">:]</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"sl3:"</span><span class="p">,</span> <span class="nx">l</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>We can declare and initialize a variable for slice
|
||||
in a single line as well.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">t</span> <span class="o">:=</span> <span class="p">[]</span><span class="kt">string</span><span class="p">{</span><span class="s">"g"</span><span class="p">,</span> <span class="s">"h"</span><span class="p">,</span> <span class="s">"i"</span><span class="p">}</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"dcl:"</span><span class="p">,</span> <span class="nx">t</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Slices can be composed into multi-dimensional data
|
||||
structures. The length of the inner slices can
|
||||
vary, unlike with multi-dimensional arrays.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre> <span class="nx">twoD</span> <span class="o">:=</span> <span class="nb">make</span><span class="p">([][]</span><span class="kt">int</span><span class="p">,</span> <span class="mi">3</span><span class="p">)</span>
|
||||
<span class="k">for</span> <span class="nx">i</span> <span class="o">:=</span> <span class="mi">0</span><span class="p">;</span> <span class="nx">i</span> <span class="p"><</span> <span class="mi">3</span><span class="p">;</span> <span class="nx">i</span><span class="o">++</span> <span class="p">{</span>
|
||||
<span class="nx">innerLen</span> <span class="o">:=</span> <span class="nx">i</span> <span class="o">+</span> <span class="mi">1</span>
|
||||
<span class="nx">twoD</span><span class="p">[</span><span class="nx">i</span><span class="p">]</span> <span class="p">=</span> <span class="nb">make</span><span class="p">([]</span><span class="kt">int</span><span class="p">,</span> <span class="nx">innerLen</span><span class="p">)</span>
|
||||
<span class="k">for</span> <span class="nx">j</span> <span class="o">:=</span> <span class="mi">0</span><span class="p">;</span> <span class="nx">j</span> <span class="p"><</span> <span class="nx">innerLen</span><span class="p">;</span> <span class="nx">j</span><span class="o">++</span> <span class="p">{</span>
|
||||
<span class="nx">twoD</span><span class="p">[</span><span class="nx">i</span><span class="p">][</span><span class="nx">j</span><span class="p">]</span> <span class="p">=</span> <span class="nx">i</span> <span class="o">+</span> <span class="nx">j</span>
|
||||
<span class="p">}</span>
|
||||
<span class="p">}</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"2d: "</span><span class="p">,</span> <span class="nx">twoD</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Note that while slices are different types than arrays,
|
||||
they are rendered similarly by <code>fmt.Println</code>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run slices.go
|
||||
<span class="go">emp: [ ]</span>
|
||||
<span class="go">set: [a b c]</span>
|
||||
<span class="go">get: c</span>
|
||||
<span class="go">len: 3</span>
|
||||
<span class="go">apd: [a b c d e f]</span>
|
||||
<span class="go">cpy: [a b c d e f]</span>
|
||||
<span class="go">sl1: [c d e]</span>
|
||||
<span class="go">sl2: [a b c d e]</span>
|
||||
<span class="go">sl3: [c d e f]</span>
|
||||
<span class="go">dcl: [g h i]</span>
|
||||
<span class="go">2d: [[0] [1 2] [2 3 4]]</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Check out this <a href="http://blog.golang.org/2011/01/go-slices-usage-and-internals.html">great blog post</a>
|
||||
by the Go team for more details on the design and
|
||||
implementation of slices in Go.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Now that we’ve seen arrays and slices we’ll look at
|
||||
Go’s other key builtin data structure: maps.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="maps">Maps</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/slices">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
150
public/sorting
Normal file
150
public/sorting
Normal file
@ -0,0 +1,150 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Sorting</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="sorting">
|
||||
<h2><a href="./">Go by Example</a>: Sorting</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Go’s <code>sort</code> package implements sorting for builtins
|
||||
and user-defined types. We’ll look at sorting for
|
||||
builtins first.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
<span class="kn">import</span> <span class="s">"sort"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Sort methods are specific to the builtin type;
|
||||
here’s an example for strings. Note that sorting is
|
||||
in-place, so it changes the given slice and doesn’t
|
||||
return a new one.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">strs</span> <span class="o">:=</span> <span class="p">[]</span><span class="kt">string</span><span class="p">{</span><span class="s">"c"</span><span class="p">,</span> <span class="s">"a"</span><span class="p">,</span> <span class="s">"b"</span><span class="p">}</span>
|
||||
<span class="nx">sort</span><span class="p">.</span><span class="nx">Strings</span><span class="p">(</span><span class="nx">strs</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"Strings:"</span><span class="p">,</span> <span class="nx">strs</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>An example of sorting <code>int</code>s.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">ints</span> <span class="o">:=</span> <span class="p">[]</span><span class="kt">int</span><span class="p">{</span><span class="mi">7</span><span class="p">,</span> <span class="mi">2</span><span class="p">,</span> <span class="mi">4</span><span class="p">}</span>
|
||||
<span class="nx">sort</span><span class="p">.</span><span class="nx">Ints</span><span class="p">(</span><span class="nx">ints</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"Ints: "</span><span class="p">,</span> <span class="nx">ints</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>We can also use <code>sort</code> to check if a slice is
|
||||
already in sorted order.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre> <span class="nx">s</span> <span class="o">:=</span> <span class="nx">sort</span><span class="p">.</span><span class="nx">IntsAreSorted</span><span class="p">(</span><span class="nx">ints</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"Sorted: "</span><span class="p">,</span> <span class="nx">s</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Running our program prints the sorted string and int
|
||||
slices and <code>true</code> as the result of our <code>AreSorted</code> test.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run sorting.go
|
||||
<span class="go">Strings: [a b c]</span>
|
||||
<span class="go">Ints: [2 4 7]</span>
|
||||
<span class="go">Sorted: true</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="sorting-by-functions">Sorting by Functions</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/sorting">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
167
public/sorting-by-functions
Normal file
167
public/sorting-by-functions
Normal file
@ -0,0 +1,167 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Sorting by Functions</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="sorting-by-functions">
|
||||
<h2><a href="./">Go by Example</a>: Sorting by Functions</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Sometimes we’ll want to sort a collection by something
|
||||
other than its natural order. For example, suppose we
|
||||
wanted to sort strings by their length instead of
|
||||
alphabetically. Here’s an example of custom sorts sorts
|
||||
in Go.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"sort"</span>
|
||||
<span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>In order to sort by a custom function in Go, we need a
|
||||
corresponding type. Here we’ve created a <code>ByLength</code>
|
||||
type that is just an alias for the builtin <code>[]string</code>
|
||||
type.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">type</span> <span class="nx">ByLength</span> <span class="p">[]</span><span class="kt">string</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>We implement <code>sort.Interface</code> - <code>Len</code>, <code>Less</code>, and
|
||||
<code>Swap</code> - on our type so we can use the <code>sort</code> package’s
|
||||
generic <code>Sort</code> function. <code>Len</code> and <code>Swap</code>
|
||||
will usually be similar accross types and <code>Less</code> will
|
||||
hold the actual custom sorting logic. In our case we
|
||||
want to sort in order of increasing string length, so
|
||||
we use <code>len(s[i])</code> and <code>len(s[j])</code> here.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="p">(</span><span class="nx">s</span> <span class="nx">ByLength</span><span class="p">)</span> <span class="nx">Len</span><span class="p">()</span> <span class="kt">int</span> <span class="p">{</span>
|
||||
<span class="k">return</span> <span class="nb">len</span><span class="p">(</span><span class="nx">s</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
<span class="kd">func</span> <span class="p">(</span><span class="nx">s</span> <span class="nx">ByLength</span><span class="p">)</span> <span class="nx">Swap</span><span class="p">(</span><span class="nx">i</span><span class="p">,</span> <span class="nx">j</span> <span class="kt">int</span><span class="p">)</span> <span class="p">{</span>
|
||||
<span class="nx">s</span><span class="p">[</span><span class="nx">i</span><span class="p">],</span> <span class="nx">s</span><span class="p">[</span><span class="nx">j</span><span class="p">]</span> <span class="p">=</span> <span class="nx">s</span><span class="p">[</span><span class="nx">j</span><span class="p">],</span> <span class="nx">s</span><span class="p">[</span><span class="nx">i</span><span class="p">]</span>
|
||||
<span class="p">}</span>
|
||||
<span class="kd">func</span> <span class="p">(</span><span class="nx">s</span> <span class="nx">ByLength</span><span class="p">)</span> <span class="nx">Less</span><span class="p">(</span><span class="nx">i</span><span class="p">,</span> <span class="nx">j</span> <span class="kt">int</span><span class="p">)</span> <span class="kt">bool</span> <span class="p">{</span>
|
||||
<span class="k">return</span> <span class="nb">len</span><span class="p">(</span><span class="nx">s</span><span class="p">[</span><span class="nx">i</span><span class="p">])</span> <span class="p"><</span> <span class="nb">len</span><span class="p">(</span><span class="nx">s</span><span class="p">[</span><span class="nx">j</span><span class="p">])</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>With all of this in place, we can now implement our
|
||||
custom sort by casting the original <code>fruits</code> slice to
|
||||
<code>ByLength</code>, and then use <code>sort.Sort</code> on that typed
|
||||
slice.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
<span class="nx">fruits</span> <span class="o">:=</span> <span class="p">[]</span><span class="kt">string</span><span class="p">{</span><span class="s">"peach"</span><span class="p">,</span> <span class="s">"banana"</span><span class="p">,</span> <span class="s">"kiwi"</span><span class="p">}</span>
|
||||
<span class="nx">sort</span><span class="p">.</span><span class="nx">Sort</span><span class="p">(</span><span class="nx">ByLength</span><span class="p">(</span><span class="nx">fruits</span><span class="p">))</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">fruits</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Running our program shows a list sorted by string
|
||||
length, as desired.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run sorting-by-functions.go
|
||||
<span class="go">[kiwi peach banana]</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>By following this same pattern of creating a custom
|
||||
type, implementing the three <code>Interface</code> methods on that
|
||||
type, and then calling sort.Sort on a collection of that
|
||||
custom type, we can sort Go slices by arbitrary
|
||||
functions.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="panic">Panic</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/sorting-by-functions">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
244
public/spawning-processes
Normal file
244
public/spawning-processes
Normal file
@ -0,0 +1,244 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Spawning Processes</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="spawning-processes">
|
||||
<h2><a href="./">Go by Example</a>: Spawning Processes</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Sometimes our Go programs need to spawn other, non-Go
|
||||
processes. For example, the syntax highlighting on this
|
||||
site is <a href="https://github.com/mmcgrana/gobyexample/blob/master/tools/generate.go">implemented</a>
|
||||
by spawning a <a href="http://pygments.org/"><code>pygmentize</code></a>
|
||||
process from a Go program. Let’s look at a few examples
|
||||
of spawning processes from Go.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
<span class="kn">import</span> <span class="s">"io/ioutil"</span>
|
||||
<span class="kn">import</span> <span class="s">"os/exec"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>We’ll start with a simple command that takes no
|
||||
arguments or input and just prints something to
|
||||
stdout. The <code>exec.Command</code> helper creates an object
|
||||
to represent this external process.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">dateCmd</span> <span class="o">:=</span> <span class="nx">exec</span><span class="p">.</span><span class="nx">Command</span><span class="p">(</span><span class="s">"date"</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p><code>.Output</code> is another helper than handles the common
|
||||
case of running a command, waiting for it to finish,
|
||||
and collecting its output. If there were no errors,
|
||||
<code>dateOut</code> will hold bytes with the date info.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">dateOut</span><span class="p">,</span> <span class="nx">err</span> <span class="o">:=</span> <span class="nx">dateCmd</span><span class="p">.</span><span class="nx">Output</span><span class="p">()</span>
|
||||
<span class="k">if</span> <span class="nx">err</span> <span class="o">!=</span> <span class="kc">nil</span> <span class="p">{</span>
|
||||
<span class="nb">panic</span><span class="p">(</span><span class="nx">err</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"> date"</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nb">string</span><span class="p">(</span><span class="nx">dateOut</span><span class="p">))</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Next we’ll look at a slightly more involved case
|
||||
where we pipe data to the external process on its
|
||||
<code>stdin</code> and collect the results from its <code>stdout</code>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">grepCmd</span> <span class="o">:=</span> <span class="nx">exec</span><span class="p">.</span><span class="nx">Command</span><span class="p">(</span><span class="s">"grep"</span><span class="p">,</span> <span class="s">"hello"</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Here we explicitly grab input/output pipes, start
|
||||
the process, write some input to it, read the
|
||||
resulting output, and finally wait for the process
|
||||
to exit.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">grepIn</span><span class="p">,</span> <span class="nx">_</span> <span class="o">:=</span> <span class="nx">grepCmd</span><span class="p">.</span><span class="nx">StdinPipe</span><span class="p">()</span>
|
||||
<span class="nx">grepOut</span><span class="p">,</span> <span class="nx">_</span> <span class="o">:=</span> <span class="nx">grepCmd</span><span class="p">.</span><span class="nx">StdoutPipe</span><span class="p">()</span>
|
||||
<span class="nx">grepCmd</span><span class="p">.</span><span class="nx">Start</span><span class="p">()</span>
|
||||
<span class="nx">grepIn</span><span class="p">.</span><span class="nx">Write</span><span class="p">([]</span><span class="nb">byte</span><span class="p">(</span><span class="s">"hello grep\ngoodbye grep"</span><span class="p">))</span>
|
||||
<span class="nx">grepIn</span><span class="p">.</span><span class="nx">Close</span><span class="p">()</span>
|
||||
<span class="nx">grepBytes</span><span class="p">,</span> <span class="nx">_</span> <span class="o">:=</span> <span class="nx">ioutil</span><span class="p">.</span><span class="nx">ReadAll</span><span class="p">(</span><span class="nx">grepOut</span><span class="p">)</span>
|
||||
<span class="nx">grepCmd</span><span class="p">.</span><span class="nx">Wait</span><span class="p">()</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>We ommited error checks in the above example, but
|
||||
you could use the usual <code>if err != nil</code> pattern for
|
||||
all of them. We also only collect the <code>StdoutPipe</code>
|
||||
results, but you could collect the <code>StderrPipe</code> in
|
||||
exactly the same way.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"> grep hello"</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nb">string</span><span class="p">(</span><span class="nx">grepBytes</span><span class="p">))</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Note that when spawning commands we need to
|
||||
provide an explicitly delineated command and
|
||||
argument array, vs. being able to just pass in one
|
||||
command-line string. If you want to spawn a full
|
||||
command with a string, you can use <code>bash</code>’s <code>-c</code>
|
||||
option:</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre> <span class="nx">lsCmd</span> <span class="o">:=</span> <span class="nx">exec</span><span class="p">.</span><span class="nx">Command</span><span class="p">(</span><span class="s">"bash"</span><span class="p">,</span> <span class="s">"-c"</span><span class="p">,</span> <span class="s">"ls -a -l -h"</span><span class="p">)</span>
|
||||
<span class="nx">lsOut</span><span class="p">,</span> <span class="nx">err</span> <span class="o">:=</span> <span class="nx">lsCmd</span><span class="p">.</span><span class="nx">Output</span><span class="p">()</span>
|
||||
<span class="k">if</span> <span class="nx">err</span> <span class="o">!=</span> <span class="kc">nil</span> <span class="p">{</span>
|
||||
<span class="nb">panic</span><span class="p">(</span><span class="nx">err</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"> ls -a -l -h"</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nb">string</span><span class="p">(</span><span class="nx">lsOut</span><span class="p">))</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>The spawned programs return output that is the same
|
||||
as if we had run them directly from the command-line.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run spawning-processes.go
|
||||
<span class="gp">></span> date
|
||||
<span class="go">Wed Oct 10 09:53:11 PDT 2012</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="gp">></span> grep hello
|
||||
<span class="go">hello grep</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre><span class="gp">></span> ls -a -l -h
|
||||
<span class="go">drwxr-xr-x 4 mark 136B Oct 3 16:29 .</span>
|
||||
<span class="go">drwxr-xr-x 91 mark 3.0K Oct 3 12:50 ..</span>
|
||||
<span class="go">-rw-r--r-- 1 mark 1.3K Oct 3 16:28 spawning-processes.go</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="execing-processes">Exec'ing Processes</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/spawning-processes">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
303
public/stateful-goroutines
Normal file
303
public/stateful-goroutines
Normal file
@ -0,0 +1,303 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Stateful Goroutines</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="stateful-goroutines">
|
||||
<h2><a href="./">Go by Example</a>: Stateful Goroutines</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>In the previous example we used explicit locking with
|
||||
mutexes to synchronize access to shared state across
|
||||
multiple goroutines. Another option is to use the
|
||||
built-in synchronization features of goroutines and
|
||||
channels to achieve the same result. This channel-based
|
||||
approach aligns with Go’s ideas of sharing memory by
|
||||
communicating and having each piece of data owned
|
||||
by exactly 1 goroutine.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="p">(</span>
|
||||
<span class="s">"fmt"</span>
|
||||
<span class="s">"math/rand"</span>
|
||||
<span class="s">"sync/atomic"</span>
|
||||
<span class="s">"time"</span>
|
||||
<span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>In this example our state will be owned by a single
|
||||
goroutine. This will guarantee that the data is never
|
||||
corrupted with concurrent access. In order to read or
|
||||
write that state, other goroutines will send messages
|
||||
to the owning goroutine and receive corresponding
|
||||
replies. These <code>readOp</code> and <code>writeOp</code> <code>struct</code>s
|
||||
encapsulate those requests and a way for the owning
|
||||
goroutine to respond.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">type</span> <span class="nx">readOp</span> <span class="kd">struct</span> <span class="p">{</span>
|
||||
<span class="nx">key</span> <span class="kt">int</span>
|
||||
<span class="nx">resp</span> <span class="kd">chan</span> <span class="kt">int</span>
|
||||
<span class="p">}</span>
|
||||
<span class="kd">type</span> <span class="nx">writeOp</span> <span class="kd">struct</span> <span class="p">{</span>
|
||||
<span class="nx">key</span> <span class="kt">int</span>
|
||||
<span class="nx">val</span> <span class="kt">int</span>
|
||||
<span class="nx">resp</span> <span class="kd">chan</span> <span class="kt">bool</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>The <code>state</code> will be a map as in the previous
|
||||
example.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="kd">var</span> <span class="nx">state</span> <span class="p">=</span> <span class="nb">make</span><span class="p">(</span><span class="kd">map</span><span class="p">[</span><span class="kt">int</span><span class="p">]</span><span class="kt">int</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Also as before we’ll count how many operations we
|
||||
perform.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="kd">var</span> <span class="nx">ops</span> <span class="kt">int64</span> <span class="p">=</span> <span class="mi">0</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>The <code>reads</code> and <code>writes</code> channels will be used by
|
||||
other goroutines to issue read and write requests,
|
||||
respectively.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">reads</span> <span class="o">:=</span> <span class="nb">make</span><span class="p">(</span><span class="kd">chan</span> <span class="o">*</span><span class="nx">readOp</span><span class="p">)</span>
|
||||
<span class="nx">writes</span> <span class="o">:=</span> <span class="nb">make</span><span class="p">(</span><span class="kd">chan</span> <span class="o">*</span><span class="nx">writeOp</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Here is the goroutine that owns the <code>state</code>. This
|
||||
goroutine repeatedly selects on the <code>reads</code> and
|
||||
<code>writes</code> channels, responding to requests as they
|
||||
arrive. A response is executed by first performing
|
||||
the requested operation and then sending a value
|
||||
on the response channel <code>resp</code> to indicate success
|
||||
(and the desired value in the case of <code>reads</code>).</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="k">go</span> <span class="kd">func</span><span class="p">()</span> <span class="p">{</span>
|
||||
<span class="k">for</span> <span class="p">{</span>
|
||||
<span class="k">select</span> <span class="p">{</span>
|
||||
<span class="k">case</span> <span class="nx">read</span> <span class="o">:=</span> <span class="o"><-</span><span class="nx">reads</span><span class="p">:</span>
|
||||
<span class="nx">read</span><span class="p">.</span><span class="nx">resp</span> <span class="o"><-</span> <span class="nx">state</span><span class="p">[</span><span class="nx">read</span><span class="p">.</span><span class="nx">key</span><span class="p">]</span>
|
||||
<span class="k">case</span> <span class="nx">write</span> <span class="o">:=</span> <span class="o"><-</span><span class="nx">writes</span><span class="p">:</span>
|
||||
<span class="nx">state</span><span class="p">[</span><span class="nx">write</span><span class="p">.</span><span class="nx">key</span><span class="p">]</span> <span class="p">=</span> <span class="nx">write</span><span class="p">.</span><span class="nx">val</span>
|
||||
<span class="nx">write</span><span class="p">.</span><span class="nx">resp</span> <span class="o"><-</span> <span class="kc">true</span>
|
||||
<span class="p">}</span>
|
||||
<span class="p">}</span>
|
||||
<span class="p">}()</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>This starts 100 goroutines to issue reads to the
|
||||
state-owning goroutine via the <code>reads</code> channel.
|
||||
Each read requires constructing a <code>readOp</code>, sending
|
||||
it over the <code>reads</code> channel, and the receiving the
|
||||
result over the provided <code>resp</code> channel.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="k">for</span> <span class="nx">r</span> <span class="o">:=</span> <span class="mi">0</span><span class="p">;</span> <span class="nx">r</span> <span class="p"><</span> <span class="mi">100</span><span class="p">;</span> <span class="nx">r</span><span class="o">++</span> <span class="p">{</span>
|
||||
<span class="k">go</span> <span class="kd">func</span><span class="p">()</span> <span class="p">{</span>
|
||||
<span class="k">for</span> <span class="p">{</span>
|
||||
<span class="nx">read</span> <span class="o">:=</span> <span class="o">&</span><span class="nx">readOp</span><span class="p">{</span>
|
||||
<span class="nx">key</span><span class="p">:</span> <span class="nx">rand</span><span class="p">.</span><span class="nx">Intn</span><span class="p">(</span><span class="mi">5</span><span class="p">),</span>
|
||||
<span class="nx">resp</span><span class="p">:</span> <span class="nb">make</span><span class="p">(</span><span class="kd">chan</span> <span class="kt">int</span><span class="p">)}</span>
|
||||
<span class="nx">reads</span> <span class="o"><-</span> <span class="nx">read</span>
|
||||
<span class="o"><-</span><span class="nx">read</span><span class="p">.</span><span class="nx">resp</span>
|
||||
<span class="nx">atomic</span><span class="p">.</span><span class="nx">AddInt64</span><span class="p">(</span><span class="o">&</span><span class="nx">ops</span><span class="p">,</span> <span class="mi">1</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
<span class="p">}()</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>We start 10 writes as well, using a similar
|
||||
approach.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="k">for</span> <span class="nx">w</span> <span class="o">:=</span> <span class="mi">0</span><span class="p">;</span> <span class="nx">w</span> <span class="p"><</span> <span class="mi">10</span><span class="p">;</span> <span class="nx">w</span><span class="o">++</span> <span class="p">{</span>
|
||||
<span class="k">go</span> <span class="kd">func</span><span class="p">()</span> <span class="p">{</span>
|
||||
<span class="k">for</span> <span class="p">{</span>
|
||||
<span class="nx">write</span> <span class="o">:=</span> <span class="o">&</span><span class="nx">writeOp</span><span class="p">{</span>
|
||||
<span class="nx">key</span><span class="p">:</span> <span class="nx">rand</span><span class="p">.</span><span class="nx">Intn</span><span class="p">(</span><span class="mi">5</span><span class="p">),</span>
|
||||
<span class="nx">val</span><span class="p">:</span> <span class="nx">rand</span><span class="p">.</span><span class="nx">Intn</span><span class="p">(</span><span class="mi">100</span><span class="p">),</span>
|
||||
<span class="nx">resp</span><span class="p">:</span> <span class="nb">make</span><span class="p">(</span><span class="kd">chan</span> <span class="kt">bool</span><span class="p">)}</span>
|
||||
<span class="nx">writes</span> <span class="o"><-</span> <span class="nx">write</span>
|
||||
<span class="o"><-</span><span class="nx">write</span><span class="p">.</span><span class="nx">resp</span>
|
||||
<span class="nx">atomic</span><span class="p">.</span><span class="nx">AddInt64</span><span class="p">(</span><span class="o">&</span><span class="nx">ops</span><span class="p">,</span> <span class="mi">1</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
<span class="p">}()</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Let the goroutines work for a second.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">time</span><span class="p">.</span><span class="nx">Sleep</span><span class="p">(</span><span class="nx">time</span><span class="p">.</span><span class="nx">Second</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Finally, capture and report the <code>ops</code> count.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre> <span class="nx">opsFinal</span> <span class="o">:=</span> <span class="nx">atomic</span><span class="p">.</span><span class="nx">LoadInt64</span><span class="p">(</span><span class="o">&</span><span class="nx">ops</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"ops:"</span><span class="p">,</span> <span class="nx">opsFinal</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Running our program shows that the goroutine-based
|
||||
state management example achieves about 800,000
|
||||
operations per second.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run stateful-goroutines.go
|
||||
<span class="go">ops: 807434</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>For this particular case the goroutine-based approach
|
||||
was a bit more involved than the mutex-based one. It
|
||||
might be useful in certain cases though, for example
|
||||
where you have other channels involved or when managing
|
||||
multiple such mutexes would be error-prone. You should
|
||||
use whichever approach feels most natural, especially
|
||||
with respect to understanding the correctness of your
|
||||
program.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="sorting">Sorting</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/stateful-goroutines">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
427
public/string-formatting
Normal file
427
public/string-formatting
Normal file
@ -0,0 +1,427 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: String Formatting</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="string-formatting">
|
||||
<h2><a href="./">Go by Example</a>: String Formatting</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Go offers excellent support for string formatting in
|
||||
the <code>printf</code> tradition. Here are some examples of
|
||||
common string formatting tasks.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
<span class="kn">import</span> <span class="s">"os"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">type</span> <span class="nx">point</span> <span class="kd">struct</span> <span class="p">{</span>
|
||||
<span class="nx">x</span><span class="p">,</span> <span class="nx">y</span> <span class="kt">int</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Go offers several printing “verbs” designed to
|
||||
format general Go values. For example, this prints
|
||||
an instance of our <code>point</code> struct.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">p</span> <span class="o">:=</span> <span class="nx">point</span><span class="p">{</span><span class="mi">1</span><span class="p">,</span> <span class="mi">2</span><span class="p">}</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Printf</span><span class="p">(</span><span class="s">"%v\n"</span><span class="p">,</span> <span class="nx">p</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>If the value is a struct, the <code>%+v</code> variant will
|
||||
include the struct’s field names.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Printf</span><span class="p">(</span><span class="s">"%+v\n"</span><span class="p">,</span> <span class="nx">p</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>The <code>%#v</code> variant prints a Go syntax representation
|
||||
of the value, i.e. the source code snippet that
|
||||
would produce that value.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Printf</span><span class="p">(</span><span class="s">"%#v\n"</span><span class="p">,</span> <span class="nx">p</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>To print the type of a value, use <code>%T</code>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Printf</span><span class="p">(</span><span class="s">"%T\n"</span><span class="p">,</span> <span class="nx">p</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Formatting booleans is straight-forward.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Printf</span><span class="p">(</span><span class="s">"%t\n"</span><span class="p">,</span> <span class="kc">true</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>There are many options for formatting integers.
|
||||
Use <code>%d</code> for standard, base-10 formatting.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Printf</span><span class="p">(</span><span class="s">"%d\n"</span><span class="p">,</span> <span class="mi">123</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>This prints a binary representation.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Printf</span><span class="p">(</span><span class="s">"%b\n"</span><span class="p">,</span> <span class="mi">14</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>This prints the character corresponding to the
|
||||
given integer.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Printf</span><span class="p">(</span><span class="s">"%c\n"</span><span class="p">,</span> <span class="mi">33</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p><code>%x</code> provides hex encoding.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Printf</span><span class="p">(</span><span class="s">"%x\n"</span><span class="p">,</span> <span class="mi">456</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>There are also several formatting options for
|
||||
floats. For basic decimal formatting use <code>%f</code>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Printf</span><span class="p">(</span><span class="s">"%f\n"</span><span class="p">,</span> <span class="mf">78.9</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p><code>%e</code> and <code>%E</code> format the float in (slightly
|
||||
different versions of) scientific notation.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Printf</span><span class="p">(</span><span class="s">"%e\n"</span><span class="p">,</span> <span class="mf">123400000.0</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Printf</span><span class="p">(</span><span class="s">"%E\n"</span><span class="p">,</span> <span class="mf">123400000.0</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>For basic string printing use <code>%s</code>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Printf</span><span class="p">(</span><span class="s">"%s\n"</span><span class="p">,</span> <span class="s">"\"string\""</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>To double-quote strings as in Go source, use <code>%q</code>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Printf</span><span class="p">(</span><span class="s">"%q\n"</span><span class="p">,</span> <span class="s">"\"string\""</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>As with integers as seen earlier, <code>%x</code> renders
|
||||
the string in base-16, with two output characters
|
||||
per byte of input.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Printf</span><span class="p">(</span><span class="s">"%x\n"</span><span class="p">,</span> <span class="s">"hex this"</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>To print a representation of a pointer, use <code>%p</code>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Printf</span><span class="p">(</span><span class="s">"%p\n"</span><span class="p">,</span> <span class="o">&</span><span class="nx">p</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>When formatting numbers you will often want to
|
||||
control the width and precision of the resulting
|
||||
figure. To specify the width of an integer, use a
|
||||
number after the <code>%</code> in the verb. By default the
|
||||
result will be right-justified and padded with
|
||||
spaces.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Printf</span><span class="p">(</span><span class="s">"|%6d|%6d|\n"</span><span class="p">,</span> <span class="mi">12</span><span class="p">,</span> <span class="mi">345</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>You can also specify the width of printed floats,
|
||||
though usually you’ll also want to restrict the
|
||||
decimal precision at the same time with the
|
||||
width.precision syntax.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Printf</span><span class="p">(</span><span class="s">"|%6.2f|%6.2f|\n"</span><span class="p">,</span> <span class="mf">1.2</span><span class="p">,</span> <span class="mf">3.45</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>To left-justify, use the <code>-</code> flag.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Printf</span><span class="p">(</span><span class="s">"|%-6.2f|%-6.2f|\n"</span><span class="p">,</span> <span class="mf">1.2</span><span class="p">,</span> <span class="mf">3.45</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>You may also want to control width when formatting
|
||||
strings, especially to ensure that they align in
|
||||
table-like output. For basic right-justified width.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Printf</span><span class="p">(</span><span class="s">"|%6s|%6s|\n"</span><span class="p">,</span> <span class="s">"foo"</span><span class="p">,</span> <span class="s">"b"</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>To left-justify use the <code>-</code> flag as with numbers.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Printf</span><span class="p">(</span><span class="s">"|%-6s|%-6s|\n"</span><span class="p">,</span> <span class="s">"foo"</span><span class="p">,</span> <span class="s">"b"</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>So far we’ve seen <code>Printf</code>, which prints the
|
||||
formatted string to <code>os.Stdout</code>. <code>Sprintf</code> formats
|
||||
and returns a string without printing it anywhere.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">s</span> <span class="o">:=</span> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Sprintf</span><span class="p">(</span><span class="s">"a %s"</span><span class="p">,</span> <span class="s">"string"</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">s</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>You can format+print to <code>io.Writers</code> other than
|
||||
<code>os.Stdout</code> using <code>Fprintf</code>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Fprintf</span><span class="p">(</span><span class="nx">os</span><span class="p">.</span><span class="nx">Stderr</span><span class="p">,</span> <span class="s">"an %s\n"</span><span class="p">,</span> <span class="s">"error"</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run string-formatting.go
|
||||
<span class="go">{1 2}</span>
|
||||
<span class="go">{x:1 y:2}</span>
|
||||
<span class="go">main.point{x:1, y:2}</span>
|
||||
<span class="go">main.point</span>
|
||||
<span class="go">true</span>
|
||||
<span class="go">123</span>
|
||||
<span class="go">1110</span>
|
||||
<span class="go">!</span>
|
||||
<span class="go">1c8</span>
|
||||
<span class="go">78.900000</span>
|
||||
<span class="go">1.234000e+08</span>
|
||||
<span class="go">1.234000E+08</span>
|
||||
<span class="go">"string"</span>
|
||||
<span class="go">"\"string\""</span>
|
||||
<span class="go">6865782074686973</span>
|
||||
<span class="go">0x42135100</span>
|
||||
<span class="go">| 12| 345|</span>
|
||||
<span class="go">| 1.20| 3.45|</span>
|
||||
<span class="go">|1.20 |3.45 |</span>
|
||||
<span class="go">| foo| b|</span>
|
||||
<span class="go">|foo |b |</span>
|
||||
<span class="go">a string</span>
|
||||
<span class="go">an error</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="regular-expressions">Regular Expressions</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/string-formatting">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
191
public/string-functions
Normal file
191
public/string-functions
Normal file
@ -0,0 +1,191 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: String Functions</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="string-functions">
|
||||
<h2><a href="./">Go by Example</a>: String Functions</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>The standard library’s <code>strings</code> package provides many
|
||||
useful string-related functions. Here are some examples
|
||||
to give you a sense of the package.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="nx">s</span> <span class="s">"strings"</span>
|
||||
<span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>We alias <code>fmt.Println</code> to a shorter name as we’ll use
|
||||
it a lot below.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">var</span> <span class="nx">p</span> <span class="p">=</span> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Here’s a sample of the functions available in
|
||||
<code>strings</code>. Note that these are all functions from
|
||||
package, not methods on the string object itself.
|
||||
This means that we need pass the string in question
|
||||
as the first argument to the function.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">p</span><span class="p">(</span><span class="s">"Contains: "</span><span class="p">,</span> <span class="nx">s</span><span class="p">.</span><span class="nx">Contains</span><span class="p">(</span><span class="s">"test"</span><span class="p">,</span> <span class="s">"es"</span><span class="p">))</span>
|
||||
<span class="nx">p</span><span class="p">(</span><span class="s">"Count: "</span><span class="p">,</span> <span class="nx">s</span><span class="p">.</span><span class="nx">Count</span><span class="p">(</span><span class="s">"test"</span><span class="p">,</span> <span class="s">"t"</span><span class="p">))</span>
|
||||
<span class="nx">p</span><span class="p">(</span><span class="s">"HasPrefix: "</span><span class="p">,</span> <span class="nx">s</span><span class="p">.</span><span class="nx">HasPrefix</span><span class="p">(</span><span class="s">"test"</span><span class="p">,</span> <span class="s">"te"</span><span class="p">))</span>
|
||||
<span class="nx">p</span><span class="p">(</span><span class="s">"HasSuffix: "</span><span class="p">,</span> <span class="nx">s</span><span class="p">.</span><span class="nx">HasSuffix</span><span class="p">(</span><span class="s">"test"</span><span class="p">,</span> <span class="s">"st"</span><span class="p">))</span>
|
||||
<span class="nx">p</span><span class="p">(</span><span class="s">"Index: "</span><span class="p">,</span> <span class="nx">s</span><span class="p">.</span><span class="nx">Index</span><span class="p">(</span><span class="s">"test"</span><span class="p">,</span> <span class="s">"e"</span><span class="p">))</span>
|
||||
<span class="nx">p</span><span class="p">(</span><span class="s">"Join: "</span><span class="p">,</span> <span class="nx">s</span><span class="p">.</span><span class="nx">Join</span><span class="p">([]</span><span class="kt">string</span><span class="p">{</span><span class="s">"a"</span><span class="p">,</span> <span class="s">"b"</span><span class="p">},</span> <span class="s">"-"</span><span class="p">))</span>
|
||||
<span class="nx">p</span><span class="p">(</span><span class="s">"Repeat: "</span><span class="p">,</span> <span class="nx">s</span><span class="p">.</span><span class="nx">Repeat</span><span class="p">(</span><span class="s">"a"</span><span class="p">,</span> <span class="mi">5</span><span class="p">))</span>
|
||||
<span class="nx">p</span><span class="p">(</span><span class="s">"Replace: "</span><span class="p">,</span> <span class="nx">s</span><span class="p">.</span><span class="nx">Replace</span><span class="p">(</span><span class="s">"foo"</span><span class="p">,</span> <span class="s">"o"</span><span class="p">,</span> <span class="s">"0"</span><span class="p">,</span> <span class="o">-</span><span class="mi">1</span><span class="p">))</span>
|
||||
<span class="nx">p</span><span class="p">(</span><span class="s">"Replace: "</span><span class="p">,</span> <span class="nx">s</span><span class="p">.</span><span class="nx">Replace</span><span class="p">(</span><span class="s">"foo"</span><span class="p">,</span> <span class="s">"o"</span><span class="p">,</span> <span class="s">"0"</span><span class="p">,</span> <span class="mi">1</span><span class="p">))</span>
|
||||
<span class="nx">p</span><span class="p">(</span><span class="s">"Split: "</span><span class="p">,</span> <span class="nx">s</span><span class="p">.</span><span class="nx">Split</span><span class="p">(</span><span class="s">"a-b-c-d-e"</span><span class="p">,</span> <span class="s">"-"</span><span class="p">))</span>
|
||||
<span class="nx">p</span><span class="p">(</span><span class="s">"toLower: "</span><span class="p">,</span> <span class="nx">s</span><span class="p">.</span><span class="nx">ToLower</span><span class="p">(</span><span class="s">"TEST"</span><span class="p">))</span>
|
||||
<span class="nx">p</span><span class="p">(</span><span class="s">"ToUpper: "</span><span class="p">,</span> <span class="nx">s</span><span class="p">.</span><span class="nx">ToUpper</span><span class="p">(</span><span class="s">"test"</span><span class="p">))</span>
|
||||
<span class="nx">p</span><span class="p">()</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>You can find more functions in the <a href="http://golang.org/pkg/strings/"><code>strings</code></a>
|
||||
package docs.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Not part of <code>strings</code> but worth mentioning here are
|
||||
the mechanisms for getting the length of a string
|
||||
and getting a character by index.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre> <span class="nx">p</span><span class="p">(</span><span class="s">"Len: "</span><span class="p">,</span> <span class="nb">len</span><span class="p">(</span><span class="s">"hello"</span><span class="p">))</span>
|
||||
<span class="nx">p</span><span class="p">(</span><span class="s">"Char:"</span><span class="p">,</span> <span class="s">"hello"</span><span class="p">[</span><span class="mi">1</span><span class="p">])</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run string-functions.go
|
||||
<span class="go">Contains: true</span>
|
||||
<span class="go">Count: 2</span>
|
||||
<span class="go">HasPrefix: true</span>
|
||||
<span class="go">HasSuffix: true</span>
|
||||
<span class="go">Index: 1</span>
|
||||
<span class="go">Join: a-b</span>
|
||||
<span class="go">Repeat: aaaaa</span>
|
||||
<span class="go">Replace: f00</span>
|
||||
<span class="go">Replace: f0o</span>
|
||||
<span class="go">Split: [a b c d e]</span>
|
||||
<span class="go">toLower: test</span>
|
||||
<span class="go">ToUpper: TEST</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre><span class="go">Len: 5</span>
|
||||
<span class="go">Char: 101</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="string-formatting">String Formatting</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/string-functions">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
209
public/structs
Normal file
209
public/structs
Normal file
@ -0,0 +1,209 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Structs</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="structs">
|
||||
<h2><a href="./">Go by Example</a>: Structs</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Go’s <em>structs</em> are typed collections of fields.
|
||||
They’re useful for grouping data together to form
|
||||
records.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>This <code>person</code> struct type has <code>name</code> and <code>age</code> fields.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">type</span> <span class="nx">person</span> <span class="kd">struct</span> <span class="p">{</span>
|
||||
<span class="nx">name</span> <span class="kt">string</span>
|
||||
<span class="nx">age</span> <span class="kt">int</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>This syntax creates a new struct.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">person</span><span class="p">{</span><span class="s">"Bob"</span><span class="p">,</span> <span class="mi">20</span><span class="p">})</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>You can name the fields when initializing a struct.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">person</span><span class="p">{</span><span class="nx">name</span><span class="p">:</span> <span class="s">"Alice"</span><span class="p">,</span> <span class="nx">age</span><span class="p">:</span> <span class="mi">30</span><span class="p">})</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Omitted fields will be zero-valued.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">person</span><span class="p">{</span><span class="nx">name</span><span class="p">:</span> <span class="s">"Fred"</span><span class="p">})</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>An <code>&</code> prefix yields a pointer to the struct.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="o">&</span><span class="nx">person</span><span class="p">{</span><span class="nx">name</span><span class="p">:</span> <span class="s">"Ann"</span><span class="p">,</span> <span class="nx">age</span><span class="p">:</span> <span class="mi">40</span><span class="p">})</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Access struct fields with a dot.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">s</span> <span class="o">:=</span> <span class="nx">person</span><span class="p">{</span><span class="nx">name</span><span class="p">:</span> <span class="s">"Sean"</span><span class="p">,</span> <span class="nx">age</span><span class="p">:</span> <span class="mi">50</span><span class="p">}</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">s</span><span class="p">.</span><span class="nx">name</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>You can also use dots with struct pointers - the
|
||||
pointers are automatically dereferenced.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">sp</span> <span class="o">:=</span> <span class="o">&</span><span class="nx">s</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">sp</span><span class="p">.</span><span class="nx">age</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Structs are mutable.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre> <span class="nx">sp</span><span class="p">.</span><span class="nx">age</span> <span class="p">=</span> <span class="mi">51</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">sp</span><span class="p">.</span><span class="nx">age</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run structs.go
|
||||
<span class="go">{Bob 20}</span>
|
||||
<span class="go">{Alice 30}</span>
|
||||
<span class="go">{Fred 0}</span>
|
||||
<span class="go">&{Ann 40}</span>
|
||||
<span class="go">Sean</span>
|
||||
<span class="go">50</span>
|
||||
<span class="go">51</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="methods">Methods</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/structs">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
162
public/switch
Normal file
162
public/switch
Normal file
@ -0,0 +1,162 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Switch</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="switch">
|
||||
<h2><a href="./">Go by Example</a>: Switch</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p><em>Switch statements</em> express conditionals across many
|
||||
branches.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
<span class="kn">import</span> <span class="s">"time"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Here’s a basic <code>switch</code>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">i</span> <span class="o">:=</span> <span class="mi">2</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Print</span><span class="p">(</span><span class="s">"write "</span><span class="p">,</span> <span class="nx">i</span><span class="p">,</span> <span class="s">" as "</span><span class="p">)</span>
|
||||
<span class="k">switch</span> <span class="nx">i</span> <span class="p">{</span>
|
||||
<span class="k">case</span> <span class="mi">1</span><span class="p">:</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"one"</span><span class="p">)</span>
|
||||
<span class="k">case</span> <span class="mi">2</span><span class="p">:</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"two"</span><span class="p">)</span>
|
||||
<span class="k">case</span> <span class="mi">3</span><span class="p">:</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"three"</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>You can use commas to separate multiple expressions
|
||||
in the same <code>case</code> statement. We use the optional
|
||||
<code>default</code> case in this example as well.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="k">switch</span> <span class="nx">time</span><span class="p">.</span><span class="nx">Now</span><span class="p">().</span><span class="nx">Weekday</span><span class="p">()</span> <span class="p">{</span>
|
||||
<span class="k">case</span> <span class="nx">time</span><span class="p">.</span><span class="nx">Saturday</span><span class="p">,</span> <span class="nx">time</span><span class="p">.</span><span class="nx">Sunday</span><span class="p">:</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"it's the weekend"</span><span class="p">)</span>
|
||||
<span class="k">default</span><span class="p">:</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"it's a weekday"</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p><code>switch</code> without an expression is an alternate way
|
||||
to express if/else logic. Here we also show how the
|
||||
<code>case</code> expressions can be non-constants.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre> <span class="nx">t</span> <span class="o">:=</span> <span class="nx">time</span><span class="p">.</span><span class="nx">Now</span><span class="p">()</span>
|
||||
<span class="k">switch</span> <span class="p">{</span>
|
||||
<span class="k">case</span> <span class="nx">t</span><span class="p">.</span><span class="nx">Hour</span><span class="p">()</span> <span class="p"><</span> <span class="mi">12</span><span class="p">:</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"it's before noon"</span><span class="p">)</span>
|
||||
<span class="k">default</span><span class="p">:</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"it's after noon"</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run switch.go
|
||||
<span class="go">write 2 as two</span>
|
||||
<span class="go">it's the weekend</span>
|
||||
<span class="go">it's before noon</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="arrays">Arrays</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/switch">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
144
public/tickers
Normal file
144
public/tickers
Normal file
@ -0,0 +1,144 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Tickers</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="tickers">
|
||||
<h2><a href="./">Go by Example</a>: Tickers</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p><a href="timers">Timers</a> are for when you want to do
|
||||
something once in the future - <em>tickers</em> are for when
|
||||
you want to do something repeatedly at regular
|
||||
intervals. Here’s an example of a ticker that ticks
|
||||
periodically until we stop it.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"time"</span>
|
||||
<span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Tickers use a similar mechanism to timers: a
|
||||
channel that is sent values. Here we’ll use the
|
||||
<code>range</code> builtin on the channel to iterate over
|
||||
the values as they arrive every 500ms.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">ticker</span> <span class="o">:=</span> <span class="nx">time</span><span class="p">.</span><span class="nx">NewTicker</span><span class="p">(</span><span class="nx">time</span><span class="p">.</span><span class="nx">Millisecond</span> <span class="o">*</span> <span class="mi">500</span><span class="p">)</span>
|
||||
<span class="k">go</span> <span class="kd">func</span><span class="p">()</span> <span class="p">{</span>
|
||||
<span class="k">for</span> <span class="nx">t</span> <span class="o">:=</span> <span class="k">range</span> <span class="nx">ticker</span><span class="p">.</span><span class="nx">C</span> <span class="p">{</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"Tick at"</span><span class="p">,</span> <span class="nx">t</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
<span class="p">}()</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Tickers can be stopped like timers. Once a ticker
|
||||
is stopped it won’t receive any more values on its
|
||||
channel. We’ll stop ours after 1500ms.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre> <span class="nx">time</span><span class="p">.</span><span class="nx">Sleep</span><span class="p">(</span><span class="nx">time</span><span class="p">.</span><span class="nx">Millisecond</span> <span class="o">*</span> <span class="mi">1500</span><span class="p">)</span>
|
||||
<span class="nx">ticker</span><span class="p">.</span><span class="nx">Stop</span><span class="p">()</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"Ticker stopped"</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>When we run this program the ticker should tick 3 times
|
||||
befor we stop it.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run tickers.go
|
||||
<span class="go">Tick at 2012-09-23 11:29:56.487625 -0700 PDT</span>
|
||||
<span class="go">Tick at 2012-09-23 11:29:56.988063 -0700 PDT</span>
|
||||
<span class="go">Tick at 2012-09-23 11:29:57.488076 -0700 PDT</span>
|
||||
<span class="go">Ticker stopped</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="worker-pools">Worker Pools</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/tickers">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
254
public/time
Normal file
254
public/time
Normal file
@ -0,0 +1,254 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Time</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="time">
|
||||
<h2><a href="./">Go by Example</a>: Time</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Go’s offers extensive support for times and durations;
|
||||
here are some examples.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
<span class="kn">import</span> <span class="s">"time"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
<span class="nx">p</span> <span class="o">:=</span> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>We’ll start by getting the current time.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">now</span> <span class="o">:=</span> <span class="nx">time</span><span class="p">.</span><span class="nx">Now</span><span class="p">()</span>
|
||||
<span class="nx">p</span><span class="p">(</span><span class="nx">now</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>You can build a <code>time</code> struct by providing the
|
||||
year, month, day, etc. Times are always associated
|
||||
with a <code>Location</code>, i.e. time zone.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">then</span> <span class="o">:=</span> <span class="nx">time</span><span class="p">.</span><span class="nx">Date</span><span class="p">(</span>
|
||||
<span class="mi">2009</span><span class="p">,</span> <span class="mi">11</span><span class="p">,</span> <span class="mi">17</span><span class="p">,</span> <span class="mi">20</span><span class="p">,</span> <span class="mi">34</span><span class="p">,</span> <span class="mi">58</span><span class="p">,</span> <span class="mi">651387237</span><span class="p">,</span> <span class="nx">time</span><span class="p">.</span><span class="nx">UTC</span><span class="p">)</span>
|
||||
<span class="nx">p</span><span class="p">(</span><span class="nx">then</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>You can extract the various components of the time
|
||||
value as expected.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">p</span><span class="p">(</span><span class="nx">then</span><span class="p">.</span><span class="nx">Year</span><span class="p">())</span>
|
||||
<span class="nx">p</span><span class="p">(</span><span class="nx">then</span><span class="p">.</span><span class="nx">Month</span><span class="p">())</span>
|
||||
<span class="nx">p</span><span class="p">(</span><span class="nx">then</span><span class="p">.</span><span class="nx">Day</span><span class="p">())</span>
|
||||
<span class="nx">p</span><span class="p">(</span><span class="nx">then</span><span class="p">.</span><span class="nx">Hour</span><span class="p">())</span>
|
||||
<span class="nx">p</span><span class="p">(</span><span class="nx">then</span><span class="p">.</span><span class="nx">Minute</span><span class="p">())</span>
|
||||
<span class="nx">p</span><span class="p">(</span><span class="nx">then</span><span class="p">.</span><span class="nx">Second</span><span class="p">())</span>
|
||||
<span class="nx">p</span><span class="p">(</span><span class="nx">then</span><span class="p">.</span><span class="nx">Nanosecond</span><span class="p">())</span>
|
||||
<span class="nx">p</span><span class="p">(</span><span class="nx">then</span><span class="p">.</span><span class="nx">Location</span><span class="p">())</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>The Monday-Sunday <code>Weekday</code> is also available.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">p</span><span class="p">(</span><span class="nx">then</span><span class="p">.</span><span class="nx">Weekday</span><span class="p">())</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>These methods compare two times, testing if the
|
||||
first occurs before, after, or at the same time
|
||||
as the second, respectively.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">p</span><span class="p">(</span><span class="nx">then</span><span class="p">.</span><span class="nx">Before</span><span class="p">(</span><span class="nx">now</span><span class="p">))</span>
|
||||
<span class="nx">p</span><span class="p">(</span><span class="nx">then</span><span class="p">.</span><span class="nx">After</span><span class="p">(</span><span class="nx">now</span><span class="p">))</span>
|
||||
<span class="nx">p</span><span class="p">(</span><span class="nx">then</span><span class="p">.</span><span class="nx">Equal</span><span class="p">(</span><span class="nx">now</span><span class="p">))</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>The <code>Sub</code> methods returns a <code>Duration</code> representing
|
||||
the interval between two times.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">diff</span> <span class="o">:=</span> <span class="nx">now</span><span class="p">.</span><span class="nx">Sub</span><span class="p">(</span><span class="nx">then</span><span class="p">)</span>
|
||||
<span class="nx">p</span><span class="p">(</span><span class="nx">diff</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>We can compute the length of the duration in
|
||||
various units.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">p</span><span class="p">(</span><span class="nx">diff</span><span class="p">.</span><span class="nx">Hours</span><span class="p">())</span>
|
||||
<span class="nx">p</span><span class="p">(</span><span class="nx">diff</span><span class="p">.</span><span class="nx">Minutes</span><span class="p">())</span>
|
||||
<span class="nx">p</span><span class="p">(</span><span class="nx">diff</span><span class="p">.</span><span class="nx">Seconds</span><span class="p">())</span>
|
||||
<span class="nx">p</span><span class="p">(</span><span class="nx">diff</span><span class="p">.</span><span class="nx">Nanoseconds</span><span class="p">())</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>You can use <code>Add</code> to advance a time by a given
|
||||
duration, or with a <code>-</code> to move backwards by a
|
||||
duration.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre> <span class="nx">p</span><span class="p">(</span><span class="nx">then</span><span class="p">.</span><span class="nx">Add</span><span class="p">(</span><span class="nx">diff</span><span class="p">))</span>
|
||||
<span class="nx">p</span><span class="p">(</span><span class="nx">then</span><span class="p">.</span><span class="nx">Add</span><span class="p">(</span><span class="o">-</span><span class="nx">diff</span><span class="p">))</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run time.go
|
||||
<span class="go">2012-10-31 15:50:13.793654 +0000 UTC</span>
|
||||
<span class="go">2009-11-17 20:34:58.651387237 +0000 UTC</span>
|
||||
<span class="go">2009</span>
|
||||
<span class="go">November</span>
|
||||
<span class="go">17</span>
|
||||
<span class="go">20</span>
|
||||
<span class="go">34</span>
|
||||
<span class="go">58</span>
|
||||
<span class="go">651387237</span>
|
||||
<span class="go">UTC</span>
|
||||
<span class="go">Tuesday</span>
|
||||
<span class="go">true</span>
|
||||
<span class="go">false</span>
|
||||
<span class="go">false</span>
|
||||
<span class="go">25891h15m15.142266763s</span>
|
||||
<span class="go">25891.25420618521</span>
|
||||
<span class="go">1.5534752523711128e+06</span>
|
||||
<span class="go">9.320851514226677e+07</span>
|
||||
<span class="go">93208515142266763</span>
|
||||
<span class="go">2012-10-31 15:50:13.793654 +0000 UTC</span>
|
||||
<span class="go">2006-12-05 01:19:43.509120474 +0000 UTC</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Next we’ll look at the related idea of time relative to
|
||||
the Unix epoch.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="epoch">Epoch</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/time">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
207
public/time-formatting-parsing
Normal file
207
public/time-formatting-parsing
Normal file
@ -0,0 +1,207 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Time Formatting / Parsing</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="time-formatting-parsing">
|
||||
<h2><a href="./">Go by Example</a>: Time Formatting / Parsing</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Go supports time formatting and parsing via
|
||||
pattern-based layouts.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
<span class="kn">import</span> <span class="s">"time"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
<span class="nx">p</span> <span class="o">:=</span> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Here’s a basic example of formatting a time
|
||||
according to RFC3339.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">t</span> <span class="o">:=</span> <span class="nx">time</span><span class="p">.</span><span class="nx">Now</span><span class="p">()</span>
|
||||
<span class="nx">p</span><span class="p">(</span><span class="nx">t</span><span class="p">.</span><span class="nx">Format</span><span class="p">(</span><span class="s">"2006-01-02T15:04:05Z07:00"</span><span class="p">))</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p><code>Format</code> uses an example-based layout approach; it
|
||||
takes a formatted version of the reference time
|
||||
<code>Mon Jan 2 15:04:05 MST 2006</code> to determine the
|
||||
general pattern with which to format the given
|
||||
time. Here are a few more examples of time
|
||||
formatting.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">p</span><span class="p">(</span><span class="nx">t</span><span class="p">.</span><span class="nx">Format</span><span class="p">(</span><span class="s">"3:04PM"</span><span class="p">))</span>
|
||||
<span class="nx">p</span><span class="p">(</span><span class="nx">t</span><span class="p">.</span><span class="nx">Format</span><span class="p">(</span><span class="s">"Mon Jan _2 15:04:05 2006"</span><span class="p">))</span>
|
||||
<span class="nx">p</span><span class="p">(</span><span class="nx">t</span><span class="p">.</span><span class="nx">Format</span><span class="p">(</span><span class="s">"2006-01-02T15:04:05.999999-07:00"</span><span class="p">))</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>For purely numeric representations you can also
|
||||
use standard string formatting with the extracted
|
||||
components of the time value.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Printf</span><span class="p">(</span><span class="s">"%d-%02d-%02dT%02d:%02d:%02d-00:00\n"</span><span class="p">,</span>
|
||||
<span class="nx">t</span><span class="p">.</span><span class="nx">Year</span><span class="p">(),</span> <span class="nx">t</span><span class="p">.</span><span class="nx">Month</span><span class="p">(),</span> <span class="nx">t</span><span class="p">.</span><span class="nx">Day</span><span class="p">(),</span>
|
||||
<span class="nx">t</span><span class="p">.</span><span class="nx">Hour</span><span class="p">(),</span> <span class="nx">t</span><span class="p">.</span><span class="nx">Minute</span><span class="p">(),</span> <span class="nx">t</span><span class="p">.</span><span class="nx">Second</span><span class="p">())</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Time parsing uses the same example-based approach
|
||||
as <code>Format</code>ing. These examples parse times rendered
|
||||
with some of the layouts used above.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">withNanos</span> <span class="o">:=</span> <span class="s">"2006-01-02T15:04:05.999999999-07:00"</span>
|
||||
<span class="nx">t1</span><span class="p">,</span> <span class="nx">e</span> <span class="o">:=</span> <span class="nx">time</span><span class="p">.</span><span class="nx">Parse</span><span class="p">(</span>
|
||||
<span class="nx">withNanos</span><span class="p">,</span>
|
||||
<span class="s">"2012-11-01T22:08:41.117442+00:00"</span><span class="p">)</span>
|
||||
<span class="nx">p</span><span class="p">(</span><span class="nx">t1</span><span class="p">)</span>
|
||||
<span class="nx">kitchen</span> <span class="o">:=</span> <span class="s">"3:04PM"</span>
|
||||
<span class="nx">t2</span><span class="p">,</span> <span class="nx">e</span> <span class="o">:=</span> <span class="nx">time</span><span class="p">.</span><span class="nx">Parse</span><span class="p">(</span><span class="nx">kitchen</span><span class="p">,</span> <span class="s">"8:41PM"</span><span class="p">)</span>
|
||||
<span class="nx">p</span><span class="p">(</span><span class="nx">t2</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p><code>Parse</code> will return an error on malformed input
|
||||
explaining the parsing problem.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">ansic</span> <span class="o">:=</span> <span class="s">"Mon Jan _2 15:04:05 2006"</span>
|
||||
<span class="nx">_</span><span class="p">,</span> <span class="nx">e</span> <span class="p">=</span> <span class="nx">time</span><span class="p">.</span><span class="nx">Parse</span><span class="p">(</span><span class="nx">ansic</span><span class="p">,</span> <span class="s">"8:41PM"</span><span class="p">)</span>
|
||||
<span class="nx">p</span><span class="p">(</span><span class="nx">e</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>There are several predefined formats that you can
|
||||
use for both formatting and parsing.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre> <span class="nx">p</span><span class="p">(</span><span class="nx">t</span><span class="p">.</span><span class="nx">Format</span><span class="p">(</span><span class="nx">time</span><span class="p">.</span><span class="nx">Kitchen</span><span class="p">))</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run <span class="nb">time</span>-formatting-parsing.go
|
||||
<span class="go">2012-11-02T09:35:03-07:00</span>
|
||||
<span class="go">9:35AM</span>
|
||||
<span class="go">Fri Nov 2 09:35:03 2012</span>
|
||||
<span class="go">2012-11-02T09:35:03.982519-07:00</span>
|
||||
<span class="go">2012-11-02T09:35:03-00:00</span>
|
||||
<span class="go">0001-01-01 00:00:00 +0000 UTC</span>
|
||||
<span class="go">0000-01-01 20:41:00 +0000 UTC</span>
|
||||
<span class="go">parsing time "8:41PM" as "Mon Jan _2 15:04:05 2006": ...</span>
|
||||
<span class="go">9:35AM</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="random-numbers">Random Numbers</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/time-formatting-parsing">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
182
public/timeouts
Normal file
182
public/timeouts
Normal file
@ -0,0 +1,182 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Timeouts</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="timeouts">
|
||||
<h2><a href="./">Go by Example</a>: Timeouts</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p><em>Timeouts</em> are important for programs that connect to
|
||||
external resources or that otherwise need to bound
|
||||
execution time. Implementing timeouts in Go is easy and
|
||||
elegant thanks to channels and <code>select</code>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"time"</span>
|
||||
<span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>For our example, suppose we’re executing an external
|
||||
call that returns its result on a channel <code>c1</code>
|
||||
after 2s.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">c1</span> <span class="o">:=</span> <span class="nb">make</span><span class="p">(</span><span class="kd">chan</span> <span class="kt">string</span><span class="p">)</span>
|
||||
<span class="k">go</span> <span class="kd">func</span><span class="p">()</span> <span class="p">{</span>
|
||||
<span class="nx">time</span><span class="p">.</span><span class="nx">Sleep</span><span class="p">(</span><span class="nx">time</span><span class="p">.</span><span class="nx">Second</span> <span class="o">*</span> <span class="mi">2</span><span class="p">)</span>
|
||||
<span class="nx">c1</span> <span class="o"><-</span> <span class="s">"result 1"</span>
|
||||
<span class="p">}()</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Here’s the <code>select</code> implementing a timeout.
|
||||
<code>res := <-c1</code> awaits the result and <code><-Time.After</code>
|
||||
awaits a value to be sent after the timeout of
|
||||
1s. Since <code>select</code> proceeds with the first
|
||||
receive that’s ready, we’ll take the timeout case
|
||||
if the operation takes more than the allowed 1s.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="k">select</span> <span class="p">{</span>
|
||||
<span class="k">case</span> <span class="nx">res</span> <span class="o">:=</span> <span class="o"><-</span><span class="nx">c1</span><span class="p">:</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">res</span><span class="p">)</span>
|
||||
<span class="k">case</span> <span class="o"><-</span><span class="nx">time</span><span class="p">.</span><span class="nx">After</span><span class="p">(</span><span class="nx">time</span><span class="p">.</span><span class="nx">Second</span> <span class="o">*</span> <span class="mi">1</span><span class="p">):</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"timeout 1"</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>If we allow a longer timeout of 3s, then the receive
|
||||
from <code>c2</code> will succeed and we’ll print the result.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre> <span class="nx">c2</span> <span class="o">:=</span> <span class="nb">make</span><span class="p">(</span><span class="kd">chan</span> <span class="kt">string</span><span class="p">)</span>
|
||||
<span class="k">go</span> <span class="kd">func</span><span class="p">()</span> <span class="p">{</span>
|
||||
<span class="nx">time</span><span class="p">.</span><span class="nx">Sleep</span><span class="p">(</span><span class="nx">time</span><span class="p">.</span><span class="nx">Second</span> <span class="o">*</span> <span class="mi">2</span><span class="p">)</span>
|
||||
<span class="nx">c2</span> <span class="o"><-</span> <span class="s">"result 2"</span>
|
||||
<span class="p">}()</span>
|
||||
<span class="k">select</span> <span class="p">{</span>
|
||||
<span class="k">case</span> <span class="nx">res</span> <span class="o">:=</span> <span class="o"><-</span><span class="nx">c2</span><span class="p">:</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">res</span><span class="p">)</span>
|
||||
<span class="k">case</span> <span class="o"><-</span><span class="nx">time</span><span class="p">.</span><span class="nx">After</span><span class="p">(</span><span class="nx">time</span><span class="p">.</span><span class="nx">Second</span> <span class="o">*</span> <span class="mi">3</span><span class="p">):</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"timeout 2"</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Running this program shows the first operation timing
|
||||
out and the second succeeding.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run timeouts.go
|
||||
<span class="go">timeout 1</span>
|
||||
<span class="go">result 2</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Using this <code>select</code> timeout pattern requires
|
||||
communicating results over channels. This is a good
|
||||
idea in general because other important Go features are
|
||||
based on channels and <code>select</code>. We’ll look at two
|
||||
examples of this next: timers and tickers.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="non-blocking-channel-operations">Non-Blocking Channel Operations</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/timeouts">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
160
public/timers
Normal file
160
public/timers
Normal file
@ -0,0 +1,160 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Timers</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="timers">
|
||||
<h2><a href="./">Go by Example</a>: Timers</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>We often want to execute Go code at some point in the
|
||||
future, or repeatedly at some interval. Go’s built-in
|
||||
<em>timer</em> and <em>ticker</em> features make both of these tasks
|
||||
easy. We’ll look first at timers and then
|
||||
at <a href="tickers">tickers</a>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"time"</span>
|
||||
<span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Timers represent a single event in the future. You
|
||||
tell the timer how long you want to wait, and it
|
||||
provides a channel that will be notified at that
|
||||
time. This timer will wait 2 seconds.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">timer1</span> <span class="o">:=</span> <span class="nx">time</span><span class="p">.</span><span class="nx">NewTimer</span><span class="p">(</span><span class="nx">time</span><span class="p">.</span><span class="nx">Second</span> <span class="o">*</span> <span class="mi">2</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>The <code><-timer1.C</code> blocks on the timer’s channel <code>C</code>
|
||||
until it sends a value indicating that the timer
|
||||
expired.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="o"><-</span><span class="nx">timer1</span><span class="p">.</span><span class="nx">C</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"Timer 1 expired"</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>If you just wanted to wait, you could have used
|
||||
<code>time.Sleep</code>. One reason a timer may be useful is
|
||||
that you can cancel the timer before it expires.
|
||||
Here’s an example of that.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre> <span class="nx">timer2</span> <span class="o">:=</span> <span class="nx">time</span><span class="p">.</span><span class="nx">NewTimer</span><span class="p">(</span><span class="nx">time</span><span class="p">.</span><span class="nx">Second</span><span class="p">)</span>
|
||||
<span class="k">go</span> <span class="kd">func</span><span class="p">()</span> <span class="p">{</span>
|
||||
<span class="o"><-</span><span class="nx">timer2</span><span class="p">.</span><span class="nx">C</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"Timer 2 expired"</span><span class="p">)</span>
|
||||
<span class="p">}()</span>
|
||||
<span class="nx">stop2</span> <span class="o">:=</span> <span class="nx">timer2</span><span class="p">.</span><span class="nx">Stop</span><span class="p">()</span>
|
||||
<span class="k">if</span> <span class="nx">stop2</span> <span class="p">{</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"Timer 2 stopped"</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>The first timer will expire ~2s after we start the
|
||||
program, but the second should be stopped before it has
|
||||
a chance to expire.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run timers.go
|
||||
<span class="go">Timer 1 expired</span>
|
||||
<span class="go">Timer 2 stopped</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="tickers">Tickers</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/timers">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
222
public/url-parsing
Normal file
222
public/url-parsing
Normal file
@ -0,0 +1,222 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: URL Parsing</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="url-parsing">
|
||||
<h2><a href="./">Go by Example</a>: URL Parsing</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>URLs provide a <a href="http://adam.heroku.com/past/2010/3/30/urls_are_the_uniform_way_to_locate_resources/">uniform way to locate resources</a>.
|
||||
Here’s how to parse URLs in Go.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
<span class="kn">import</span> <span class="s">"net/url"</span>
|
||||
<span class="kn">import</span> <span class="s">"strings"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>We’ll parse this example URL, which includes a
|
||||
scheme, authentication info, host, port, path,
|
||||
query params, and query fragment.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">s</span> <span class="o">:=</span> <span class="s">"postgres://user:pass@host.com:5432/path?k=v#f"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Parse the URL and ensure there are no errors.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">u</span><span class="p">,</span> <span class="nx">err</span> <span class="o">:=</span> <span class="nx">url</span><span class="p">.</span><span class="nx">Parse</span><span class="p">(</span><span class="nx">s</span><span class="p">)</span>
|
||||
<span class="k">if</span> <span class="nx">err</span> <span class="o">!=</span> <span class="kc">nil</span> <span class="p">{</span>
|
||||
<span class="nb">panic</span><span class="p">(</span><span class="nx">err</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Accessing the scheme is straightforward.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">u</span><span class="p">.</span><span class="nx">Scheme</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p><code>User</code> contains all authentication info; call
|
||||
<code>Username</code> and <code>Password</code> on this for individual
|
||||
values.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">u</span><span class="p">.</span><span class="nx">User</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">u</span><span class="p">.</span><span class="nx">User</span><span class="p">.</span><span class="nx">Username</span><span class="p">())</span>
|
||||
<span class="nx">p</span><span class="p">,</span> <span class="nx">_</span> <span class="o">:=</span> <span class="nx">u</span><span class="p">.</span><span class="nx">User</span><span class="p">.</span><span class="nx">Password</span><span class="p">()</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">p</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>The <code>Host</code> contains both the hostname and the port,
|
||||
if present. <code>Split</code> the <code>Host</code> manually to extract
|
||||
the port.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">u</span><span class="p">.</span><span class="nx">Host</span><span class="p">)</span>
|
||||
<span class="nx">h</span> <span class="o">:=</span> <span class="nx">strings</span><span class="p">.</span><span class="nx">Split</span><span class="p">(</span><span class="nx">u</span><span class="p">.</span><span class="nx">Host</span><span class="p">,</span> <span class="s">":"</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">h</span><span class="p">[</span><span class="mi">0</span><span class="p">])</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">h</span><span class="p">[</span><span class="mi">1</span><span class="p">])</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Here we extract the <code>path</code> and the fragment after
|
||||
the <code>#</code>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">u</span><span class="p">.</span><span class="nx">Path</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">u</span><span class="p">.</span><span class="nx">Fragment</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>To get query params in a string of <code>k=v</code> format,
|
||||
use <code>RawQuery</code>. You can also parse query params
|
||||
into a map. The parsed query param maps are from
|
||||
strings to slices of strings, so index into <code>[0]</code>
|
||||
if you only want the first value.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">u</span><span class="p">.</span><span class="nx">RawQuery</span><span class="p">)</span>
|
||||
<span class="nx">m</span><span class="p">,</span> <span class="nx">_</span> <span class="o">:=</span> <span class="nx">url</span><span class="p">.</span><span class="nx">ParseQuery</span><span class="p">(</span><span class="nx">u</span><span class="p">.</span><span class="nx">RawQuery</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">m</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">m</span><span class="p">[</span><span class="s">"k"</span><span class="p">][</span><span class="mi">0</span><span class="p">])</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Running our URL parsing program shows all the different
|
||||
pieces that we extracted.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run url-parsing.go
|
||||
<span class="go">postgres</span>
|
||||
<span class="go">user:pass</span>
|
||||
<span class="go">user</span>
|
||||
<span class="go">pass</span>
|
||||
<span class="go">host.com:5432</span>
|
||||
<span class="go">host.com</span>
|
||||
<span class="go">5432</span>
|
||||
<span class="go">/path</span>
|
||||
<span class="go">f</span>
|
||||
<span class="go">k=v</span>
|
||||
<span class="go">map[k:[v]]</span>
|
||||
<span class="go">v</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="sha1-hashes">SHA1 Hashes</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/url-parsing">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
144
public/values
Normal file
144
public/values
Normal file
@ -0,0 +1,144 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Values</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="values">
|
||||
<h2><a href="./">Go by Example</a>: Values</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Go has various value types including strings,
|
||||
integers, floats, booleans, etc. Here are a few
|
||||
basic examples.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Strings, which can be added together with <code>+</code>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"go"</span> <span class="o">+</span> <span class="s">"lang"</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Integers and floats.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"1+1 ="</span><span class="p">,</span> <span class="mi">1</span><span class="o">+</span><span class="mi">1</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"7.0/3.0 ="</span><span class="p">,</span> <span class="mf">7.0</span><span class="o">/</span><span class="mf">3.0</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Booleans, with boolean operators as you’d expect.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre> <span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="kc">true</span> <span class="o">&&</span> <span class="kc">false</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="kc">true</span> <span class="o">||</span> <span class="kc">false</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(!</span><span class="kc">true</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run values.go
|
||||
<span class="go">golang</span>
|
||||
<span class="go">1+1 = 2</span>
|
||||
<span class="go">7.0/3.0 = 2.3333333333333335</span>
|
||||
<span class="go">false</span>
|
||||
<span class="go">true</span>
|
||||
<span class="go">false</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="variables">Variables</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/values">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
173
public/variables
Normal file
173
public/variables
Normal file
@ -0,0 +1,173 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Variables</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="variables">
|
||||
<h2><a href="./">Go by Example</a>: Variables</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>In Go, <em>variables</em> are explicitly declared and used by
|
||||
the compiler to e.g. check type-correctness of function
|
||||
calls.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p><code>var</code> declares 1 or more variables.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="kd">var</span> <span class="nx">a</span> <span class="kt">string</span> <span class="p">=</span> <span class="s">"initial"</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">a</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>You can declare multiple variables at once.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="kd">var</span> <span class="nx">b</span><span class="p">,</span> <span class="nx">c</span> <span class="kt">int</span> <span class="p">=</span> <span class="mi">1</span><span class="p">,</span> <span class="mi">2</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">b</span><span class="p">,</span> <span class="nx">c</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Go will infer the type of initialized variables.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="kd">var</span> <span class="nx">d</span> <span class="p">=</span> <span class="kc">true</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">d</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Variables declared without a corresponding
|
||||
initialization are <em>zero-valued</em>. For example, the
|
||||
zero value for an <code>int</code> is <code>0</code>.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="kd">var</span> <span class="nx">e</span> <span class="kt">int</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">e</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>The <code>:=</code> syntax is shorthand for declaring and
|
||||
initializing a variable, e.g. for
|
||||
<code>var f string = "short"</code> in this case.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre> <span class="nx">f</span> <span class="o">:=</span> <span class="s">"short"</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">f</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run variables.go
|
||||
<span class="go">initial</span>
|
||||
<span class="go">1 2</span>
|
||||
<span class="go">true</span>
|
||||
<span class="go">0</span>
|
||||
<span class="go">short</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="constants">Constants</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/variables">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
163
public/variadic-functions
Normal file
163
public/variadic-functions
Normal file
@ -0,0 +1,163 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Variadic Functions</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="variadic-functions">
|
||||
<h2><a href="./">Go by Example</a>: Variadic Functions</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p><a href="http://en.wikipedia.org/wiki/Variadic_function"><em>Variadic functions</em></a>
|
||||
can be called with any number of trailing arguments.
|
||||
For example, <code>fmt.Println</code> is a common variadic
|
||||
function.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Here’s a function that will take an arbitrary number
|
||||
of <code>ints</code> as arguments.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">sum</span><span class="p">(</span><span class="nx">nums</span> <span class="o">...</span><span class="kt">int</span><span class="p">)</span> <span class="p">{</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Print</span><span class="p">(</span><span class="nx">nums</span><span class="p">,</span> <span class="s">" "</span><span class="p">)</span>
|
||||
<span class="nx">total</span> <span class="o">:=</span> <span class="mi">0</span>
|
||||
<span class="k">for</span> <span class="nx">_</span><span class="p">,</span> <span class="nx">num</span> <span class="o">:=</span> <span class="k">range</span> <span class="nx">nums</span> <span class="p">{</span>
|
||||
<span class="nx">total</span> <span class="o">+=</span> <span class="nx">num</span>
|
||||
<span class="p">}</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="nx">total</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Variadic functions can be called in the usual way
|
||||
with individual arguments.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">sum</span><span class="p">(</span><span class="mi">1</span><span class="p">,</span> <span class="mi">2</span><span class="p">)</span>
|
||||
<span class="nx">sum</span><span class="p">(</span><span class="mi">1</span><span class="p">,</span> <span class="mi">2</span><span class="p">,</span> <span class="mi">3</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>If you already have multiple args in a slice,
|
||||
apply them to a variadic function using
|
||||
<code>func(slice...)</code> like this.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre> <span class="nx">nums</span> <span class="o">:=</span> <span class="p">[]</span><span class="kt">int</span><span class="p">{</span><span class="mi">1</span><span class="p">,</span> <span class="mi">2</span><span class="p">,</span> <span class="mi">3</span><span class="p">,</span> <span class="mi">4</span><span class="p">}</span>
|
||||
<span class="nx">sum</span><span class="p">(</span><span class="nx">nums</span><span class="o">...</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run variadic-functions.go
|
||||
<span class="go">[1 2] 3</span>
|
||||
<span class="go">[1 2 3] 6</span>
|
||||
<span class="go">[1 2 3 4] 10</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Another key aspect of functions in Go is their ability
|
||||
to form closures, which we’ll look at next.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="closures">Closures</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/variadic-functions">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
205
public/worker-pools
Normal file
205
public/worker-pools
Normal file
@ -0,0 +1,205 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Worker Pools</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="worker-pools">
|
||||
<h2><a href="./">Go by Example</a>: Worker Pools</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>In this example we’ll look at how to implement
|
||||
a <em>worker pool</em> using goroutines and channels.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="s">"fmt"</span>
|
||||
<span class="kn">import</span> <span class="s">"time"</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Here’s the worker, of which we’ll run several
|
||||
concurrent instances. These workers will receive
|
||||
work on the <code>jobs</code> channel and send the corresponding
|
||||
results on <code>results</code>. We’ll sleep a second per job to
|
||||
simulate an expensive task.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">worker</span><span class="p">(</span><span class="nx">id</span> <span class="kt">int</span><span class="p">,</span> <span class="nx">jobs</span> <span class="o"><-</span><span class="kd">chan</span> <span class="kt">int</span><span class="p">,</span> <span class="nx">results</span> <span class="kd">chan</span><span class="o"><-</span> <span class="kt">int</span><span class="p">)</span> <span class="p">{</span>
|
||||
<span class="k">for</span> <span class="nx">j</span> <span class="o">:=</span> <span class="k">range</span> <span class="nx">jobs</span> <span class="p">{</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Println</span><span class="p">(</span><span class="s">"worker"</span><span class="p">,</span> <span class="nx">id</span><span class="p">,</span> <span class="s">"processing job"</span><span class="p">,</span> <span class="nx">j</span><span class="p">)</span>
|
||||
<span class="nx">time</span><span class="p">.</span><span class="nx">Sleep</span><span class="p">(</span><span class="nx">time</span><span class="p">.</span><span class="nx">Second</span><span class="p">)</span>
|
||||
<span class="nx">results</span> <span class="o"><-</span> <span class="nx">j</span> <span class="o">*</span> <span class="mi">2</span>
|
||||
<span class="p">}</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>In order to use our pool of workers we need to send
|
||||
them work and collect their results. We make 2
|
||||
channels for this.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">jobs</span> <span class="o">:=</span> <span class="nb">make</span><span class="p">(</span><span class="kd">chan</span> <span class="kt">int</span><span class="p">,</span> <span class="mi">100</span><span class="p">)</span>
|
||||
<span class="nx">results</span> <span class="o">:=</span> <span class="nb">make</span><span class="p">(</span><span class="kd">chan</span> <span class="kt">int</span><span class="p">,</span> <span class="mi">100</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>This starts up 3 workers, initially blocked
|
||||
because there are no jobs yet.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="k">for</span> <span class="nx">w</span> <span class="o">:=</span> <span class="mi">1</span><span class="p">;</span> <span class="nx">w</span> <span class="o"><=</span> <span class="mi">3</span><span class="p">;</span> <span class="nx">w</span><span class="o">++</span> <span class="p">{</span>
|
||||
<span class="k">go</span> <span class="nx">worker</span><span class="p">(</span><span class="nx">w</span><span class="p">,</span> <span class="nx">jobs</span><span class="p">,</span> <span class="nx">results</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Here we send 9 <code>jobs</code> and then <code>close</code> that
|
||||
channel to indicate that’s all the work we have.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="k">for</span> <span class="nx">j</span> <span class="o">:=</span> <span class="mi">1</span><span class="p">;</span> <span class="nx">j</span> <span class="o"><=</span> <span class="mi">9</span><span class="p">;</span> <span class="nx">j</span><span class="o">++</span> <span class="p">{</span>
|
||||
<span class="nx">jobs</span> <span class="o"><-</span> <span class="nx">j</span>
|
||||
<span class="p">}</span>
|
||||
<span class="nb">close</span><span class="p">(</span><span class="nx">jobs</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Finally we collect all the results of the work.</p>
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre> <span class="k">for</span> <span class="nx">a</span> <span class="o">:=</span> <span class="mi">1</span><span class="p">;</span> <span class="nx">a</span> <span class="o"><=</span> <span class="mi">9</span><span class="p">;</span> <span class="nx">a</span><span class="o">++</span> <span class="p">{</span>
|
||||
<span class="o"><-</span><span class="nx">results</span>
|
||||
<span class="p">}</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Our running program shows the 9 jobs being executed by
|
||||
various workers. The program only takes about 3 seconds
|
||||
despite doing about 9 seconds of total work because
|
||||
there are 3 workers operating concurrently.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="gp">$</span> <span class="nb">time </span>go run worker-pools.go
|
||||
<span class="go">worker 1 processing job 1</span>
|
||||
<span class="go">worker 2 processing job 2</span>
|
||||
<span class="go">worker 3 processing job 3</span>
|
||||
<span class="go">worker 1 processing job 4</span>
|
||||
<span class="go">worker 2 processing job 5</span>
|
||||
<span class="go">worker 3 processing job 6</span>
|
||||
<span class="go">worker 1 processing job 7</span>
|
||||
<span class="go">worker 2 processing job 8</span>
|
||||
<span class="go">worker 3 processing job 9</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre><span class="go">real 0m3.149s</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="rate-limiting">Rate Limiting</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/worker-pools">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
270
public/writing-files
Normal file
270
public/writing-files
Normal file
@ -0,0 +1,270 @@
|
||||
<!DOCTYPE html>
|
||||
<html>
|
||||
<head>
|
||||
<meta http-eqiv="content-type" content="text/html;charset=utf-8">
|
||||
<title>Go by Example: Writing Files</title>
|
||||
<link rel=stylesheet href="site.css">
|
||||
</head>
|
||||
<script type="text/javascript">
|
||||
if (window.location.host == "gobyexample.com") {
|
||||
var _gaq = _gaq || [];
|
||||
_gaq.push(['_setAccount', 'UA-34996217-1']);
|
||||
_gaq.push(['_trackPageview']);
|
||||
(function() {
|
||||
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
|
||||
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
|
||||
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
|
||||
})();
|
||||
}
|
||||
</script>
|
||||
<body>
|
||||
<div class="example" id="writing-files">
|
||||
<h2><a href="./">Go by Example</a>: Writing Files</h2>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Writing files in Go follows similar patterns to the
|
||||
ones we saw earlier for reading.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty leading">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kn">import</span> <span class="p">(</span>
|
||||
<span class="s">"bufio"</span>
|
||||
<span class="s">"fmt"</span>
|
||||
<span class="s">"io/ioutil"</span>
|
||||
<span class="s">"os"</span>
|
||||
<span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">check</span><span class="p">(</span><span class="nx">e</span> <span class="kt">error</span><span class="p">)</span> <span class="p">{</span>
|
||||
<span class="k">if</span> <span class="nx">e</span> <span class="o">!=</span> <span class="kc">nil</span> <span class="p">{</span>
|
||||
<span class="nb">panic</span><span class="p">(</span><span class="nx">e</span><span class="p">)</span>
|
||||
<span class="p">}</span>
|
||||
<span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>To start, here’s how to dump a string (or just
|
||||
bytes) into a file.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">d1</span> <span class="o">:=</span> <span class="p">[]</span><span class="nb">byte</span><span class="p">(</span><span class="s">"hello\ngo\n"</span><span class="p">)</span>
|
||||
<span class="nx">err</span> <span class="o">:=</span> <span class="nx">ioutil</span><span class="p">.</span><span class="nx">WriteFile</span><span class="p">(</span><span class="s">"/tmp/dat1"</span><span class="p">,</span> <span class="nx">d1</span><span class="p">,</span> <span class="mo">0644</span><span class="p">)</span>
|
||||
<span class="nx">check</span><span class="p">(</span><span class="nx">err</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>For more granular writes, open a file for writing.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">f</span><span class="p">,</span> <span class="nx">err</span> <span class="o">:=</span> <span class="nx">os</span><span class="p">.</span><span class="nx">Create</span><span class="p">(</span><span class="s">"/tmp/dat2"</span><span class="p">)</span>
|
||||
<span class="nx">check</span><span class="p">(</span><span class="nx">err</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>It’s idiomatic to defer a <code>Close</code> immediately
|
||||
after opening a file.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="k">defer</span> <span class="nx">f</span><span class="p">.</span><span class="nx">Close</span><span class="p">()</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>You can <code>Write</code> byte slices as you’d expect.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">d2</span> <span class="o">:=</span> <span class="p">[]</span><span class="kt">byte</span><span class="p">{</span><span class="mi">115</span><span class="p">,</span> <span class="mi">111</span><span class="p">,</span> <span class="mi">109</span><span class="p">,</span> <span class="mi">101</span><span class="p">,</span> <span class="mi">10</span><span class="p">}</span>
|
||||
<span class="nx">n2</span><span class="p">,</span> <span class="nx">err</span> <span class="o">:=</span> <span class="nx">f</span><span class="p">.</span><span class="nx">Write</span><span class="p">(</span><span class="nx">d2</span><span class="p">)</span>
|
||||
<span class="nx">check</span><span class="p">(</span><span class="nx">err</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Printf</span><span class="p">(</span><span class="s">"wrote %d bytes\n"</span><span class="p">,</span> <span class="nx">n2</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>A <code>WriteString</code> is also available.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">n3</span><span class="p">,</span> <span class="nx">err</span> <span class="o">:=</span> <span class="nx">f</span><span class="p">.</span><span class="nx">WriteString</span><span class="p">(</span><span class="s">"writes\n"</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Printf</span><span class="p">(</span><span class="s">"wrote %d bytes\n"</span><span class="p">,</span> <span class="nx">n3</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Issue a <code>Sync</code> to flush writes to stable storage.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">f</span><span class="p">.</span><span class="nx">Sync</span><span class="p">()</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p><code>bufio</code> provides buffered writers in addition
|
||||
to the buffered readers we saw earlier.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">w</span> <span class="o">:=</span> <span class="nx">bufio</span><span class="p">.</span><span class="nx">NewWriter</span><span class="p">(</span><span class="nx">f</span><span class="p">)</span>
|
||||
<span class="nx">n4</span><span class="p">,</span> <span class="nx">err</span> <span class="o">:=</span> <span class="nx">w</span><span class="p">.</span><span class="nx">WriteString</span><span class="p">(</span><span class="s">"buffered\n"</span><span class="p">)</span>
|
||||
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Printf</span><span class="p">(</span><span class="s">"wrote %d bytes\n"</span><span class="p">,</span> <span class="nx">n4</span><span class="p">)</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Use <code>Flush</code> to ensure all buffered operations have
|
||||
been applied to the underlying writer.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre> <span class="nx">w</span><span class="p">.</span><span class="nx">Flush</span><span class="p">()</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
|
||||
</td>
|
||||
<td class="code">
|
||||
<div class="highlight"><pre><span class="p">}</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
<table>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Try running the file-writing code.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="gp">$</span> go run writing-files.go
|
||||
<span class="go">wrote 5 bytes</span>
|
||||
<span class="go">wrote 7 bytes</span>
|
||||
<span class="go">wrote 9 bytes</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Then check the contents of the written files.</p>
|
||||
|
||||
</td>
|
||||
<td class="code leading">
|
||||
<div class="highlight"><pre><span class="gp">$</span> cat /tmp/dat1
|
||||
<span class="go">hello</span>
|
||||
<span class="go">go</span>
|
||||
<span class="gp">$</span> cat /tmp/dat2
|
||||
<span class="go">some</span>
|
||||
<span class="go">writes</span>
|
||||
<span class="go">buffered</span>
|
||||
</pre></div>
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
<tr>
|
||||
<td class="docs">
|
||||
<p>Next we’ll look at applying some of the file I/O ideas
|
||||
we’ve just seen to the <code>stdin</code> and <code>stdout</code> streams.</p>
|
||||
|
||||
</td>
|
||||
<td class="code empty">
|
||||
|
||||
</td>
|
||||
</tr>
|
||||
|
||||
</table>
|
||||
|
||||
|
||||
<p class="next">
|
||||
Next example: <a href="line-filters">Line Filters</a>.
|
||||
</p>
|
||||
|
||||
<p class="footer">
|
||||
<a href="https://twitter.com/gobyexample">@gobyexample</a> | <a href="mailto:mmcgrana@gmail.com">feedback</a> | <a href="https://github.com/mmcgrana/gobyexample/blob/master/examples/writing-files">source</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a>
|
||||
</p>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
207
server.go
Normal file
207
server.go
Normal file
@ -0,0 +1,207 @@
|
||||
package main
|
||||
|
||||
import (
|
||||
"code.google.com/p/gorilla/mux"
|
||||
"encoding/base64"
|
||||
"fmt"
|
||||
"io/ioutil"
|
||||
"net"
|
||||
"net/http"
|
||||
"os"
|
||||
"os/signal"
|
||||
"strings"
|
||||
"sync/atomic"
|
||||
"syscall"
|
||||
"time"
|
||||
)
|
||||
|
||||
func check(err error) {
|
||||
if err != nil {
|
||||
panic(err)
|
||||
}
|
||||
}
|
||||
|
||||
func config(k string) string {
|
||||
v := os.Getenv(k)
|
||||
if v == "" {
|
||||
panic("missing " + k)
|
||||
}
|
||||
return v
|
||||
}
|
||||
|
||||
func runLogging(logs chan string) {
|
||||
for log := range logs {
|
||||
fmt.Println(log)
|
||||
}
|
||||
}
|
||||
|
||||
func wrapLogging(f http.HandlerFunc, logs chan string) http.HandlerFunc {
|
||||
return func(res http.ResponseWriter, req *http.Request) {
|
||||
start := time.Now()
|
||||
f(res, req)
|
||||
method := req.Method
|
||||
path := req.URL.Path
|
||||
elapsed := float64(time.Since(start)) / 1000000.0
|
||||
logs <- fmt.Sprintf("request at=finish method=%s path=%s elapsed=%f", method, path, elapsed)
|
||||
}
|
||||
}
|
||||
|
||||
func wrapCanonicalHost(f http.HandlerFunc, canonicalHost string, forceHttps bool) http.HandlerFunc {
|
||||
return func(res http.ResponseWriter, req *http.Request) {
|
||||
scheme := "http"
|
||||
if h, ok := req.Header["X-Forwarded-Proto"]; ok {
|
||||
if h[0] == "https" {
|
||||
scheme = "https"
|
||||
}
|
||||
}
|
||||
|
||||
hostPort := strings.Split(req.Host, ":")
|
||||
host := hostPort[0]
|
||||
|
||||
if (forceHttps && (scheme != "https")) || host != canonicalHost {
|
||||
if forceHttps {
|
||||
scheme = "https"
|
||||
}
|
||||
hostPort[0] = canonicalHost
|
||||
url := scheme + "://" + strings.Join(hostPort, ":") + req.URL.String()
|
||||
http.Redirect(res, req, url, 301)
|
||||
return
|
||||
}
|
||||
|
||||
f(res, req)
|
||||
}
|
||||
}
|
||||
|
||||
type Authenticator func(string, string) bool
|
||||
|
||||
func testAuth(r *http.Request, auth Authenticator) bool {
|
||||
s := strings.SplitN(r.Header.Get("Authorization"), " ", 2)
|
||||
if len(s) != 2 || s[0] != "Basic" {
|
||||
return false
|
||||
}
|
||||
b, err := base64.StdEncoding.DecodeString(s[1])
|
||||
if err != nil {
|
||||
return false
|
||||
}
|
||||
pair := strings.SplitN(string(b), ":", 2)
|
||||
if len(pair) != 2 {
|
||||
return false
|
||||
}
|
||||
return auth(pair[0], pair[1])
|
||||
}
|
||||
|
||||
func requireAuth(w http.ResponseWriter, r *http.Request) {
|
||||
w.Header().Set("WWW-Authenticate", `Basic realm="private"`)
|
||||
w.WriteHeader(401)
|
||||
w.Write([]byte("401 Unauthorized\n"))
|
||||
}
|
||||
|
||||
func wrapAuth(h http.HandlerFunc, a Authenticator) http.HandlerFunc {
|
||||
return func(w http.ResponseWriter, r *http.Request) {
|
||||
if testAuth(r, a) {
|
||||
h(w, r)
|
||||
} else {
|
||||
requireAuth(w, r)
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
var reqCount int64 = 0
|
||||
|
||||
func wrapReqCount(h http.HandlerFunc, reqCountPtr *int64) http.HandlerFunc {
|
||||
return func(w http.ResponseWriter, r *http.Request) {
|
||||
atomic.AddInt64(reqCountPtr, 1)
|
||||
h(w, r)
|
||||
atomic.AddInt64(reqCountPtr, -1)
|
||||
}
|
||||
}
|
||||
|
||||
func static(res http.ResponseWriter, req *http.Request) {
|
||||
http.ServeFile(res, req, "public"+req.URL.Path)
|
||||
}
|
||||
|
||||
func notFound(res http.ResponseWriter, req *http.Request) {
|
||||
http.ServeFile(res, req, "public/404.html")
|
||||
}
|
||||
|
||||
func checkAuth(user, pass string) bool {
|
||||
auth := os.Getenv("AUTH")
|
||||
if auth == "" {
|
||||
return true
|
||||
}
|
||||
return auth == strings.Join([]string{user, pass}, ":")
|
||||
}
|
||||
|
||||
func routerHandlerFunc(router *mux.Router) http.HandlerFunc {
|
||||
return func(res http.ResponseWriter, req *http.Request) {
|
||||
router.ServeHTTP(res, req)
|
||||
}
|
||||
}
|
||||
|
||||
func router() *mux.Router {
|
||||
router := mux.NewRouter()
|
||||
router.HandleFunc("/", static).Methods("GET")
|
||||
router.HandleFunc("/favicon.ico", static).Methods("GET")
|
||||
router.HandleFunc("/site.css", static).Methods("GET")
|
||||
entries, err := ioutil.ReadDir("public")
|
||||
check(err)
|
||||
for _, f := range entries {
|
||||
if !strings.Contains(f.Name(), ".") {
|
||||
router.HandleFunc("/" + f.Name(), static).Methods("GET")
|
||||
}
|
||||
}
|
||||
router.NotFoundHandler = http.HandlerFunc(notFound)
|
||||
return router
|
||||
}
|
||||
|
||||
func main() {
|
||||
logs := make(chan string, 10000)
|
||||
go runLogging(logs)
|
||||
|
||||
handler := routerHandlerFunc(router())
|
||||
if os.Getenv("AUTH") != "" {
|
||||
handler = wrapAuth(handler, checkAuth)
|
||||
}
|
||||
handler = wrapCanonicalHost(handler, config("CANONICAL_HOST"), config("FORCE_HTTPS") == "1")
|
||||
handler = wrapLogging(handler, logs)
|
||||
handler = wrapReqCount(handler, &reqCount)
|
||||
|
||||
server := &http.Server{Handler: handler}
|
||||
listener, listenErr := net.Listen("tcp", ":"+config("PORT"))
|
||||
if listenErr != nil {
|
||||
panic(listenErr)
|
||||
}
|
||||
|
||||
stop := make(chan bool, 1)
|
||||
sig := make(chan os.Signal, 1)
|
||||
go func() {
|
||||
signal.Notify(sig, syscall.SIGINT, syscall.SIGTERM)
|
||||
logs <- "trap at=start"
|
||||
<-sig
|
||||
for {
|
||||
reqCountCurrent := atomic.LoadInt64(&reqCount)
|
||||
if reqCountCurrent > 0 {
|
||||
logs <- fmt.Sprintf("trap at=draining remaining=%d", reqCountCurrent)
|
||||
time.Sleep(time.Second)
|
||||
} else {
|
||||
logs <- fmt.Sprintf("trap at=finish")
|
||||
stop <- true
|
||||
return
|
||||
}
|
||||
}
|
||||
}()
|
||||
|
||||
go func() {
|
||||
logs <- "serve at=start"
|
||||
server.Serve(listener)
|
||||
logs <- "serve at=finish"
|
||||
}()
|
||||
|
||||
<-stop
|
||||
logs <- "close at=start"
|
||||
closeErr := listener.Close()
|
||||
if closeErr != nil {
|
||||
panic(closeErr)
|
||||
}
|
||||
logs <- "close at=finish"
|
||||
}
|
||||
@ -14,7 +14,7 @@ import (
|
||||
)
|
||||
|
||||
var cacheDir = "/tmp/gobyexample-cache"
|
||||
var siteDir = ""
|
||||
var siteDir = "./public"
|
||||
var pygmentizeBin = ""
|
||||
|
||||
func check(err error) {
|
||||
@ -106,15 +106,6 @@ func whichLexer(path string) string {
|
||||
return ""
|
||||
}
|
||||
|
||||
func whichSiteDir() {
|
||||
dir := os.Getenv("SITEDIR")
|
||||
if dir != "" {
|
||||
siteDir = dir
|
||||
} else {
|
||||
siteDir = "site"
|
||||
}
|
||||
}
|
||||
|
||||
func whichPygmentize() {
|
||||
bin, err := exec.LookPath("pygmentize")
|
||||
check(err)
|
||||
@ -254,9 +245,7 @@ func renderExamples(examples []*Example) {
|
||||
}
|
||||
|
||||
func main() {
|
||||
whichSiteDir()
|
||||
whichPygmentize()
|
||||
ensureDir(siteDir)
|
||||
copyFile("templates/site.css", siteDir+"/site.css")
|
||||
copyFile("templates/favicon.ico", siteDir+"/favicon.ico")
|
||||
copyFile("templates/404.html", siteDir+"/404.html")
|
||||
|
||||
Loading…
x
Reference in New Issue
Block a user