199 lines
9.1 KiB
HTML
199 lines
9.1 KiB
HTML
|
|
|||
|
|
<!DOCTYPE html>
|
|||
|
|
|
|||
|
|
<html xmlns="http://www.w3.org/1999/xhtml">
|
|||
|
|
<head>
|
|||
|
|
<meta charset="utf-8" />
|
|||
|
|
<title>__main__ — Top-level script environment — Python 3.7.4 documentation</title>
|
|||
|
|
<link rel="stylesheet" href="../_static/pydoctheme.css" type="text/css" />
|
|||
|
|
<link rel="stylesheet" href="../_static/pygments.css" type="text/css" />
|
|||
|
|
|
|||
|
|
<script type="text/javascript" id="documentation_options" data-url_root="../" src="../_static/documentation_options.js"></script>
|
|||
|
|
<script type="text/javascript" src="../_static/jquery.js"></script>
|
|||
|
|
<script type="text/javascript" src="../_static/underscore.js"></script>
|
|||
|
|
<script type="text/javascript" src="../_static/doctools.js"></script>
|
|||
|
|
<script type="text/javascript" src="../_static/language_data.js"></script>
|
|||
|
|
|
|||
|
|
<script type="text/javascript" src="../_static/sidebar.js"></script>
|
|||
|
|
|
|||
|
|
<link rel="search" type="application/opensearchdescription+xml"
|
|||
|
|
title="Search within Python 3.7.4 documentation"
|
|||
|
|
href="../_static/opensearch.xml"/>
|
|||
|
|
<link rel="author" title="About these documents" href="../about.html" />
|
|||
|
|
<link rel="index" title="Index" href="../genindex.html" />
|
|||
|
|
<link rel="search" title="Search" href="../search.html" />
|
|||
|
|
<link rel="copyright" title="Copyright" href="../copyright.html" />
|
|||
|
|
<link rel="next" title="warnings — Warning control" href="warnings.html" />
|
|||
|
|
<link rel="prev" title="builtins — Built-in objects" href="builtins.html" />
|
|||
|
|
<link rel="shortcut icon" type="image/png" href="../_static/py.png" />
|
|||
|
|
<link rel="canonical" href="https://docs.python.org/3/library/__main__.html" />
|
|||
|
|
|
|||
|
|
<script type="text/javascript" src="../_static/copybutton.js"></script>
|
|||
|
|
<script type="text/javascript" src="../_static/switchers.js"></script>
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
<style>
|
|||
|
|
@media only screen {
|
|||
|
|
table.full-width-table {
|
|||
|
|
width: 100%;
|
|||
|
|
}
|
|||
|
|
}
|
|||
|
|
</style>
|
|||
|
|
|
|||
|
|
|
|||
|
|
</head><body>
|
|||
|
|
|
|||
|
|
<div class="related" role="navigation" aria-label="related navigation">
|
|||
|
|
<h3>Navigation</h3>
|
|||
|
|
<ul>
|
|||
|
|
<li class="right" style="margin-right: 10px">
|
|||
|
|
<a href="../genindex.html" title="General Index"
|
|||
|
|
accesskey="I">index</a></li>
|
|||
|
|
<li class="right" >
|
|||
|
|
<a href="../py-modindex.html" title="Python Module Index"
|
|||
|
|
>modules</a> |</li>
|
|||
|
|
<li class="right" >
|
|||
|
|
<a href="warnings.html" title="warnings — Warning control"
|
|||
|
|
accesskey="N">next</a> |</li>
|
|||
|
|
<li class="right" >
|
|||
|
|
<a href="builtins.html" title="builtins — Built-in objects"
|
|||
|
|
accesskey="P">previous</a> |</li>
|
|||
|
|
<li><img src="../_static/py.png" alt=""
|
|||
|
|
style="vertical-align: middle; margin-top: -1px"/></li>
|
|||
|
|
<li><a href="https://www.python.org/">Python</a> »</li>
|
|||
|
|
<li>
|
|||
|
|
<span class="language_switcher_placeholder">en</span>
|
|||
|
|
<span class="version_switcher_placeholder">3.7.4</span>
|
|||
|
|
<a href="../index.html">Documentation </a> »
|
|||
|
|
</li>
|
|||
|
|
|
|||
|
|
<li class="nav-item nav-item-1"><a href="index.html" >The Python Standard Library</a> »</li>
|
|||
|
|
<li class="nav-item nav-item-2"><a href="python.html" accesskey="U">Python Runtime Services</a> »</li>
|
|||
|
|
<li class="right">
|
|||
|
|
|
|||
|
|
|
|||
|
|
<div class="inline-search" style="display: none" role="search">
|
|||
|
|
<form class="inline-search" action="../search.html" method="get">
|
|||
|
|
<input placeholder="Quick search" type="text" name="q" />
|
|||
|
|
<input type="submit" value="Go" />
|
|||
|
|
<input type="hidden" name="check_keywords" value="yes" />
|
|||
|
|
<input type="hidden" name="area" value="default" />
|
|||
|
|
</form>
|
|||
|
|
</div>
|
|||
|
|
<script type="text/javascript">$('.inline-search').show(0);</script>
|
|||
|
|
|
|
|||
|
|
</li>
|
|||
|
|
|
|||
|
|
</ul>
|
|||
|
|
</div>
|
|||
|
|
|
|||
|
|
<div class="document">
|
|||
|
|
<div class="documentwrapper">
|
|||
|
|
<div class="bodywrapper">
|
|||
|
|
<div class="body" role="main">
|
|||
|
|
|
|||
|
|
<div class="section" id="module-__main__">
|
|||
|
|
<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> — Top-level script environment<a class="headerlink" href="#module-__main__" title="Permalink to this headline">¶</a></h1>
|
|||
|
|
<hr class="docutils" />
|
|||
|
|
<p><code class="docutils literal notranslate"><span class="pre">'__main__'</span></code> is the name of the scope in which top-level code executes.
|
|||
|
|
A module’s __name__ is set equal to <code class="docutils literal notranslate"><span class="pre">'__main__'</span></code> when read from
|
|||
|
|
standard input, a script, or from an interactive prompt.</p>
|
|||
|
|
<p>A module can discover whether or not it is running in the main scope by
|
|||
|
|
checking its own <code class="docutils literal notranslate"><span class="pre">__name__</span></code>, which allows a common idiom for conditionally
|
|||
|
|
executing code in a module when it is run as a script or with <code class="docutils literal notranslate"><span class="pre">python</span>
|
|||
|
|
<span class="pre">-m</span></code> but not when it is imported:</p>
|
|||
|
|
<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>
|
|||
|
|
<span class="c1"># execute only if run as a script</span>
|
|||
|
|
<span class="n">main</span><span class="p">()</span>
|
|||
|
|
</pre></div>
|
|||
|
|
</div>
|
|||
|
|
<p>For a package, the same effect can be achieved by including a
|
|||
|
|
<code class="docutils literal notranslate"><span class="pre">__main__.py</span></code> module, the contents of which will be executed when the
|
|||
|
|
module is run with <code class="docutils literal notranslate"><span class="pre">-m</span></code>.</p>
|
|||
|
|
</div>
|
|||
|
|
|
|||
|
|
|
|||
|
|
</div>
|
|||
|
|
</div>
|
|||
|
|
</div>
|
|||
|
|
<div class="sphinxsidebar" role="navigation" aria-label="main navigation">
|
|||
|
|
<div class="sphinxsidebarwrapper">
|
|||
|
|
<h4>Previous topic</h4>
|
|||
|
|
<p class="topless"><a href="builtins.html"
|
|||
|
|
title="previous chapter"><code class="xref py py-mod docutils literal notranslate"><span class="pre">builtins</span></code> — Built-in objects</a></p>
|
|||
|
|
<h4>Next topic</h4>
|
|||
|
|
<p class="topless"><a href="warnings.html"
|
|||
|
|
title="next chapter"><code class="xref py py-mod docutils literal notranslate"><span class="pre">warnings</span></code> — Warning control</a></p>
|
|||
|
|
<div role="note" aria-label="source link">
|
|||
|
|
<h3>This Page</h3>
|
|||
|
|
<ul class="this-page-menu">
|
|||
|
|
<li><a href="../bugs.html">Report a Bug</a></li>
|
|||
|
|
<li>
|
|||
|
|
<a href="https://github.com/python/cpython/blob/3.7/Doc/library/__main__.rst"
|
|||
|
|
rel="nofollow">Show Source
|
|||
|
|
</a>
|
|||
|
|
</li>
|
|||
|
|
</ul>
|
|||
|
|
</div>
|
|||
|
|
</div>
|
|||
|
|
</div>
|
|||
|
|
<div class="clearer"></div>
|
|||
|
|
</div>
|
|||
|
|
<div class="related" role="navigation" aria-label="related navigation">
|
|||
|
|
<h3>Navigation</h3>
|
|||
|
|
<ul>
|
|||
|
|
<li class="right" style="margin-right: 10px">
|
|||
|
|
<a href="../genindex.html" title="General Index"
|
|||
|
|
>index</a></li>
|
|||
|
|
<li class="right" >
|
|||
|
|
<a href="../py-modindex.html" title="Python Module Index"
|
|||
|
|
>modules</a> |</li>
|
|||
|
|
<li class="right" >
|
|||
|
|
<a href="warnings.html" title="warnings — Warning control"
|
|||
|
|
>next</a> |</li>
|
|||
|
|
<li class="right" >
|
|||
|
|
<a href="builtins.html" title="builtins — Built-in objects"
|
|||
|
|
>previous</a> |</li>
|
|||
|
|
<li><img src="../_static/py.png" alt=""
|
|||
|
|
style="vertical-align: middle; margin-top: -1px"/></li>
|
|||
|
|
<li><a href="https://www.python.org/">Python</a> »</li>
|
|||
|
|
<li>
|
|||
|
|
<span class="language_switcher_placeholder">en</span>
|
|||
|
|
<span class="version_switcher_placeholder">3.7.4</span>
|
|||
|
|
<a href="../index.html">Documentation </a> »
|
|||
|
|
</li>
|
|||
|
|
|
|||
|
|
<li class="nav-item nav-item-1"><a href="index.html" >The Python Standard Library</a> »</li>
|
|||
|
|
<li class="nav-item nav-item-2"><a href="python.html" >Python Runtime Services</a> »</li>
|
|||
|
|
<li class="right">
|
|||
|
|
|
|||
|
|
|
|||
|
|
<div class="inline-search" style="display: none" role="search">
|
|||
|
|
<form class="inline-search" action="../search.html" method="get">
|
|||
|
|
<input placeholder="Quick search" type="text" name="q" />
|
|||
|
|
<input type="submit" value="Go" />
|
|||
|
|
<input type="hidden" name="check_keywords" value="yes" />
|
|||
|
|
<input type="hidden" name="area" value="default" />
|
|||
|
|
</form>
|
|||
|
|
</div>
|
|||
|
|
<script type="text/javascript">$('.inline-search').show(0);</script>
|
|||
|
|
|
|
|||
|
|
</li>
|
|||
|
|
|
|||
|
|
</ul>
|
|||
|
|
</div>
|
|||
|
|
<div class="footer">
|
|||
|
|
© <a href="../copyright.html">Copyright</a> 2001-2019, Python Software Foundation.
|
|||
|
|
<br />
|
|||
|
|
The Python Software Foundation is a non-profit corporation.
|
|||
|
|
<a href="https://www.python.org/psf/donations/">Please donate.</a>
|
|||
|
|
<br />
|
|||
|
|
Last updated on Jul 13, 2019.
|
|||
|
|
<a href="../bugs.html">Found a bug</a>?
|
|||
|
|
<br />
|
|||
|
|
Created using <a href="http://sphinx.pocoo.org/">Sphinx</a> 2.0.1.
|
|||
|
|
</div>
|
|||
|
|
|
|||
|
|
</body>
|
|||
|
|
</html>
|