9e216da9ef
After go1.16, go will use module mode by default, even when the repository is checked out under GOPATH or in a one-off directory. Add go.mod, go.sum to keep this repo buildable without opting out of the module mode. > go mod init github.com/mmcgrana/gobyexample > go mod tidy > go mod vendor In module mode, the 'vendor' directory is special and its contents will be actively maintained by the go command. pygments aren't the dependency the go will know about, so it will delete the contents from vendor directory. Move it to `third_party` directory now. And, vendor the blackfriday package. Note: the tutorial contents are not affected by the change in go1.16 because all the examples in this tutorial ask users to run the go command with the explicit list of files to be compiled (e.g. `go run hello-world.go` or `go build command-line-arguments.go`). When the source list is provided, the go command does not have to compute the build list and whether it's running in GOPATH mode or module mode becomes irrelevant.
153 lines
6.2 KiB
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153 lines
6.2 KiB
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Generated
<!DOCTYPE html>
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<html>
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<head>
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<meta charset="utf-8">
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<title>Go by Example: Channel Directions</title>
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<link rel=stylesheet href="site.css">
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</head>
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<script>
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onkeydown = (e) => {
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if (e.key == "ArrowLeft") {
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window.location.href = 'channel-synchronization';
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}
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if (e.key == "ArrowRight") {
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window.location.href = 'select';
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}
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}
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</script>
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<body>
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<div class="example" id="channel-directions">
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<h2><a href="./">Go by Example</a>: Channel Directions</h2>
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<table>
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<tr>
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<td class="docs">
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<p>When using channels as function parameters, you can
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specify if a channel is meant to only send or receive
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values. This specificity increases the type-safety of
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the program.</p>
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</td>
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<td class="code empty leading">
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</td>
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</tr>
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<tr>
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<td class="docs">
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</td>
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<td class="code leading">
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<a href="http://play.golang.org/p/mjNJDHwUH4R"><img title="Run code" src="play.png" class="run" /></a><img title="Copy code" src="clipboard.png" class="copy" />
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<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
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</pre></div>
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</td>
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</tr>
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<tr>
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<td class="docs">
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</td>
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<td class="code leading">
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<div class="highlight"><pre><span class="kn">import</span> <span class="s">"fmt"</span>
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</pre></div>
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</td>
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</tr>
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<tr>
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<td class="docs">
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<p>This <code>ping</code> function only accepts a channel for sending
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values. It would be a compile-time error to try to
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receive on this channel.</p>
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</td>
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<td class="code leading">
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<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>
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<span class="nx">pings</span> <span class="o"><-</span> <span class="nx">msg</span>
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<span class="p">}</span>
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</pre></div>
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</td>
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</tr>
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<tr>
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<td class="docs">
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<p>The <code>pong</code> function accepts one channel for receives
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(<code>pings</code>) and a second for sends (<code>pongs</code>).</p>
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</td>
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<td class="code leading">
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<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>
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<span class="nx">msg</span> <span class="o">:=</span> <span class="o"><-</span><span class="nx">pings</span>
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<span class="nx">pongs</span> <span class="o"><-</span> <span class="nx">msg</span>
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<span class="p">}</span>
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</pre></div>
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</td>
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</tr>
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<tr>
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<td class="docs">
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</td>
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<td class="code">
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<div class="highlight"><pre><span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
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<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>
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<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>
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<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>
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<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>
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<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>
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<span class="p">}</span>
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</pre></div>
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</td>
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</tr>
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</table>
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<table>
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<tr>
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<td class="docs">
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</td>
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<td class="code">
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<div class="highlight"><pre><span class="gp">$</span> go run channel-directions.go
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<span class="go">passed message</span>
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</pre></div>
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</td>
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</tr>
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</table>
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<p class="next">
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Next example: <a href="select">Select</a>.
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</p>
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<p class="footer">
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by <a href="https://markmcgranaghan.com">Mark McGranaghan</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>
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</p>
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</div>
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<script>
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var codeLines = [];
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codeLines.push('');codeLines.push('package main\u000A');codeLines.push('import \"fmt\"\u000A');codeLines.push('func ping(pings chan\u003C- string, msg string) {\u000A pings \u003C- msg\u000A}\u000A');codeLines.push('func pong(pings \u003C-chan string, pongs chan\u003C- string) {\u000A msg :\u003D \u003C-pings\u000A pongs \u003C- msg\u000A}\u000A');codeLines.push('func main() {\u000A pings :\u003D make(chan string, 1)\u000A pongs :\u003D make(chan string, 1)\u000A ping(pings, \"passed message\")\u000A pong(pings, pongs)\u000A fmt.Println(\u003C-pongs)\u000A}\u000A');codeLines.push('');
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</script>
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<script src="site.js" async></script>
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</body>
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</html>
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