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.
162 lines
5.2 KiB
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162 lines
5.2 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: Range over Channels</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 = 'closing-channels';
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}
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if (e.key == "ArrowRight") {
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window.location.href = 'timers';
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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="range-over-channels">
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<h2><a href="./">Go by Example</a>: Range over Channels</h2>
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<table>
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<tr>
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<td class="docs">
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<p>In a <a href="range">previous</a> example we saw how <code>for</code> and
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<code>range</code> provide iteration over basic data structures.
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We can also use this syntax to iterate over
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values received from a channel.</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/yQMclmwOYs9"><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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</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">main</span><span class="p">()</span> <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>We’ll iterate over 2 values in the <code>queue</code> 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="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>
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<span class="nx">queue</span> <span class="o"><-</span> <span class="s">"one"</span>
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<span class="nx">queue</span> <span class="o"><-</span> <span class="s">"two"</span>
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<span class="nb">close</span><span class="p">(</span><span class="nx">queue</span><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>This <code>range</code> iterates over each element as it’s
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received from <code>queue</code>. Because we <code>close</code>d the
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channel above, the iteration terminates after
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receiving the 2 elements.</p>
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</td>
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<td class="code">
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<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>
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<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>
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<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 leading">
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<div class="highlight"><pre><span class="gp">$</span> go run range-over-channels.go
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<span class="go">one</span>
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<span class="go">two</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 example also showed that it’s possible to close
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a non-empty channel but still have the remaining
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values be received.</p>
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</td>
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<td class="code empty">
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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="timers">Timers</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/range-over-channels">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 main() {\u000A');codeLines.push(' queue :\u003D make(chan string, 2)\u000A queue \u003C- \"one\"\u000A queue \u003C- \"two\"\u000A close(queue)\u000A');codeLines.push(' for elem :\u003D range queue {\u000A fmt.Println(elem)\u000A }\u000A}\u000A');codeLines.push('');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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