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<section id="module-__main__">
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<span id="main-top-level-script-environment"></span><h1><a class="reference internal" href="#module-__main__" title="__main__: The environment where the top-level script is run."><code class="xref py py-mod docutils literal notranslate"><span class="pre">__main__</span></code></a> --- 顶层脚本环境<a class="headerlink" href="#module-__main__" title="永久链接至标题">¶</a></h1>
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<p><code class="docutils literal notranslate"><span class="pre">'__main__'</span></code> 是顶层代码执行的作用域的名称。模块的 __name__ 在通过标准输入、脚本文件或是交互式命令读入的时候会等于 <code class="docutils literal notranslate"><span class="pre">'__main__'</span></code>。</p>
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<p>模块可以通过检查自己的 <code class="docutils literal notranslate"><span class="pre">__name__</span></code> 来得知是否运行在 main 作用域中，这使得模块可以在作为脚本或是通过 <code class="docutils literal notranslate"><span class="pre">python</span> <span class="pre">-m</span></code> 运行时条件性地执行一些代码，而在被 import 时不会执行。</p>
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<div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="k">if</span> <span class="vm">__name__</span> <span class="o">==</span> <span class="s2">"__main__"</span><span class="p">:</span>
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<span class="c1"># execute only if run as a script</span>
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<span class="n">main</span><span class="p">()</span>
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</pre></div>
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<p>对软件包来说，通过加入 <code class="docutils literal notranslate"><span class="pre">__main__.py</span></code> 模块可以达到同样的效果，当使用 <code class="docutils literal notranslate"><span class="pre">-m</span></code> 运行模块时，其中的代码会被执行。</p>
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最后更新于 12月 09, 2024.
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<a href="https://docs.python.org/3/bugs.html">Found a bug</a>?
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