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channel-directions.html
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<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Go by Example 中文版: 通道方向</title>
<link rel=stylesheet href="site.css">
</head>
<script>
onkeydown = (e) => {
if (e.key == "ArrowLeft") {
window.location.href = 'channel-synchronization';
}
if (e.key == "ArrowRight") {
window.location.href = 'select';
}
}
</script>
<body>
<div class="example" id="channel-directions">
<h2><a href="./">Go by Example 中文版</a>: 通道方向</h2>
<table>
<tr>
<td class="docs">
<p>当使用通道作为函数的参数时，你可以指定这个通道是否为只读或只写。
该特性可以提升程序的类型安全。</p>
</td>
<td class="code empty leading">
</td>
</tr>
<tr>
<td class="docs">
</td>
<td class="code leading">
<a href="https://play.studygolang.com/p/Y7VnAHqQiBK"><img title="Run code" src="play.png" class="run" /></a><img title="Copy code" src="clipboard.png" class="copy" />
<pre class="chroma"><span class="kn">package</span> <span class="nx">main</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
</td>
<td class="code leading">
<pre class="chroma"><span class="kn">import</span> <span class="s">"fmt"</span>
</pre>
</td>
</tr>
<tr>
<td class="docs">
<p><code>ping</code> 函数定义了一个只能发送数据的（只写）通道。
尝试从这个通道接收数据会是一个编译时错误。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="kd">func</span> <span class="nf">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>
</td>
</tr>
<tr>
<td class="docs">
<p><code>pong</code> 函数接收两个通道，<code>pings</code> 仅用于接收数据（只读），<code>pongs</code> 仅用于发送数据（只写）。</p>
</td>
<td class="code leading">
<pre class="chroma">
<span class="kd">func</span> <span class="nf">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>
</td>
</tr>
<tr>
<td class="docs">
</td>
<td class="code">
<pre class="chroma"><span class="kd">func</span> <span class="nf">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="nf">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="nf">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="nf">Println</span><span class="p">(</span><span class="o"><-</span><span class="nx">pongs</span><span class="p">)</span>
<span class="p">}</span>
</pre>
</td>
</tr>
</table>
<table>
<tr>
<td class="docs">
</td>
<td class="code">
<pre class="chroma"><span class="gp">$</span> go run channel-directions.go
<span class="go">passed message</span></pre>
</td>
</tr>
</table>
<p class="next">
下一个例子: <a href="select">通道选择器</a>
</p>
<p class="footer">
<a href="https://twitter.com/mmcgrana">@mmcgrana</a> 和<a href="https://eli.thegreenplace.net">Eli Bendersky</a>编写 | <a href="https://github.com/gobyexample-cn">gobyexample-cn</a> 翻译 | <a href="https://github.com/gobyexample-cn/gobyexample/issues">反馈</a> | <a href="https://github.com/gobyexample-cn/gobyexample">源码</a> | <a href="https://github.com/mmcgrana/gobyexample#license">license</a> </p>
</p>
</div>
<script>
var codeLines = [];
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('');
</script>
<script src="site.js" async></script>
</body>
</html>