zw/iOSAI
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity
Files
317fc2586ad37c50fd3223f11ad9ee2d5cf6ba9d
iOSAI/Needed/mini-python/Doc/html/c-api/weakref.html
milk 4966a659aa 调整目录结构
2025-10-23 18:57:37 +08:00

376 lines
24 KiB
HTML
Raw Blame History

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" /><meta name="generator" content="Docutils 0.17.1: http://docutils.sourceforge.net/" />
<meta property="og:title" content="Weak Reference Objects" />
<meta property="og:type" content="website" />
<meta property="og:url" content="https://docs.python.org/3/c-api/weakref.html" />
<meta property="og:site_name" content="Python documentation" />
<meta property="og:description" content="Python supports weak references as first-class objects. There are two specific object types which directly implement weak references. The first is a simple reference object, and the second acts as ..." />
<meta property="og:image" content="https://docs.python.org/3/_static/og-image.png" />
<meta property="og:image:alt" content="Python documentation" />
<meta name="description" content="Python supports weak references as first-class objects. There are two specific object types which directly implement weak references. The first is a simple reference object, and the second acts as ..." />
<meta property="og:image:width" content="200" />
<meta property="og:image:height" content="200" />
<meta name="theme-color" content="#3776ab" />
<title>Weak Reference Objects &#8212; Python 3.12.0 documentation</title><meta name="viewport" content="width=device-width, initial-scale=1.0">
<link rel="stylesheet" type="text/css" href="../_static/pygments.css" />
<link rel="stylesheet" type="text/css" href="../_static/pydoctheme.css?digest=b37c26da2f7529d09fe70b41c4b2133fe4931a90" />
<link id="pygments_dark_css" media="(prefers-color-scheme: dark)" rel="stylesheet" type="text/css" href="../_static/pygments_dark.css" />
<script data-url_root="../" id="documentation_options" src="../_static/documentation_options.js"></script>
<script src="../_static/jquery.js"></script>
<script src="../_static/underscore.js"></script>
<script src="../_static/doctools.js"></script>
<script src="../_static/sidebar.js"></script>
<link rel="search" type="application/opensearchdescription+xml"
title="Search within Python 3.12.0 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="Capsules" href="capsule.html" />
<link rel="prev" title="MemoryView objects" href="memoryview.html" />
<link rel="canonical" href="https://docs.python.org/3/c-api/weakref.html" />
<style>
@media only screen {
table.full-width-table {
width: 100%;
}
}
</style>
<link rel="stylesheet" href="../_static/pydoctheme_dark.css" media="(prefers-color-scheme: dark)" id="pydoctheme_dark_css">
<link rel="shortcut icon" type="image/png" href="../_static/py.svg" />
<script type="text/javascript" src="../_static/copybutton.js"></script>
<script type="text/javascript" src="../_static/menu.js"></script>
<script type="text/javascript" src="../_static/themetoggle.js"></script>
</head>
<body>
<div class="mobile-nav">
<input type="checkbox" id="menuToggler" class="toggler__input" aria-controls="navigation"
aria-pressed="false" aria-expanded="false" role="button" aria-label="Menu" />
<nav class="nav-content" role="navigation">
<label for="menuToggler" class="toggler__label">
<span></span>
</label>
<span class="nav-items-wrapper">
<a href="https://www.python.org/" class="nav-logo">
<img src="../_static/py.svg" alt="Logo"/>
</a>
<span class="version_switcher_placeholder"></span>
<form role="search" class="search" action="../search.html" method="get">
<svg xmlns="http://www.w3.org/2000/svg" width="20" height="20" viewBox="0 0 24 24" class="search-icon">
<path fill-rule="nonzero" fill="currentColor" d="M15.5 14h-.79l-.28-.27a6.5 6.5 0 001.48-5.34c-.47-2.78-2.79-5-5.59-5.34a6.505 6.505 0 00-7.27 7.27c.34 2.8 2.56 5.12 5.34 5.59a6.5 6.5 0 005.34-1.48l.27.28v.79l4.25 4.25c.41.41 1.08.41 1.49 0 .41-.41.41-1.08 0-1.49L15.5 14zm-6 0C7.01 14 5 11.99 5 9.5S7.01 5 9.5 5 14 7.01 14 9.5 11.99 14 9.5 14z"></path>
</svg>
<input placeholder="Quick search" aria-label="Quick search" type="search" name="q" />
<input type="submit" value="Go"/>
</form>
</span>
</nav>
<div class="menu-wrapper">
<nav class="menu" role="navigation" aria-label="main navigation">
<div class="language_switcher_placeholder"></div>
<label class="theme-selector-label">
Theme
<select class="theme-selector" oninput="activateTheme(this.value)">
<option value="auto" selected>Auto</option>
<option value="light">Light</option>
<option value="dark">Dark</option>
</select>
</label>
<div>
<h4>Previous topic</h4>
<p class="topless"><a href="memoryview.html"
title="previous chapter">MemoryView objects</a></p>
</div>
<div>
<h4>Next topic</h4>
<p class="topless"><a href="capsule.html"
title="next chapter">Capsules</a></p>
</div>
<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/main/Doc/c-api/weakref.rst"
rel="nofollow">Show Source
</a>
</li>
</ul>
</div>
</nav>
</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"
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="capsule.html" title="Capsules"
accesskey="N">next</a> |</li>
<li class="right" >
<a href="memoryview.html" title="MemoryView objects"
accesskey="P">previous</a> |</li>
<li><img src="../_static/py.svg" alt="python logo" style="vertical-align: middle; margin-top: -1px"/></li>
<li><a href="https://www.python.org/">Python</a> &#187;</li>
<li class="switchers">
<div class="language_switcher_placeholder"></div>
<div class="version_switcher_placeholder"></div>
</li>
<li>
</li>
<li id="cpython-language-and-version">
<a href="../index.html">3.12.0 Documentation</a> &#187;
</li>
<li class="nav-item nav-item-1"><a href="index.html" >Python/C API Reference Manual</a> &#187;</li>
<li class="nav-item nav-item-2"><a href="concrete.html" accesskey="U">Concrete Objects Layer</a> &#187;</li>
<li class="nav-item nav-item-this"><a href="">Weak Reference Objects</a></li>
<li class="right">
<div class="inline-search" role="search">
<form class="inline-search" action="../search.html" method="get">
<input placeholder="Quick search" aria-label="Quick search" type="search" name="q" />
<input type="submit" value="Go" />
</form>
</div>
|
</li>
<li class="right">
<label class="theme-selector-label">
Theme
<select class="theme-selector" oninput="activateTheme(this.value)">
<option value="auto" selected>Auto</option>
<option value="light">Light</option>
<option value="dark">Dark</option>
</select>
</label> |</li>
</ul>
</div>
<div class="document">
<div class="documentwrapper">
<div class="bodywrapper">
<div class="body" role="main">
<section id="weak-reference-objects">
<span id="weakrefobjects"></span><h1>Weak Reference Objects<a class="headerlink" href="#weak-reference-objects" title="Permalink to this headline"></a></h1>
<p>Python supports <em>weak references</em> as first-class objects. There are two
specific object types which directly implement weak references. The first is a
simple reference object, and the second acts as a proxy for the original object
as much as it can.</p>
<dl class="c function">
<dt class="sig sig-object c" id="c.PyWeakref_Check">
<span class="kt"><span class="pre">int</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">PyWeakref_Check</span></span></span><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject"><span class="n"><span class="pre">PyObject</span></span></a><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">ob</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.PyWeakref_Check" title="Permalink to this definition"></a><br /></dt>
<dd><p>Return true if <em>ob</em> is either a reference or proxy object. This function
always succeeds.</p>
</dd></dl>
<dl class="c function">
<dt class="sig sig-object c" id="c.PyWeakref_CheckRef">
<span class="kt"><span class="pre">int</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">PyWeakref_CheckRef</span></span></span><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject"><span class="n"><span class="pre">PyObject</span></span></a><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">ob</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.PyWeakref_CheckRef" title="Permalink to this definition"></a><br /></dt>
<dd><p>Return true if <em>ob</em> is a reference object. This function always succeeds.</p>
</dd></dl>
<dl class="c function">
<dt class="sig sig-object c" id="c.PyWeakref_CheckProxy">
<span class="kt"><span class="pre">int</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">PyWeakref_CheckProxy</span></span></span><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject"><span class="n"><span class="pre">PyObject</span></span></a><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">ob</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.PyWeakref_CheckProxy" title="Permalink to this definition"></a><br /></dt>
<dd><p>Return true if <em>ob</em> is a proxy object. This function always succeeds.</p>
</dd></dl>
<dl class="c function">
<dt class="sig sig-object c" id="c.PyWeakref_NewRef">
<a class="reference internal" href="structures.html#c.PyObject" title="PyObject"><span class="n"><span class="pre">PyObject</span></span></a><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="sig-name descname"><span class="n"><span class="pre">PyWeakref_NewRef</span></span></span><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject"><span class="n"><span class="pre">PyObject</span></span></a><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">ob</span></span>, <a class="reference internal" href="structures.html#c.PyObject" title="PyObject"><span class="n"><span class="pre">PyObject</span></span></a><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">callback</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.PyWeakref_NewRef" title="Permalink to this definition"></a><br /></dt>
<dd><em class="refcount">Return value: New reference.</em><em class="stableabi"> Part of the <a class="reference internal" href="stable.html#stable"><span class="std std-ref">Stable ABI</span></a>.</em><p>Return a weak reference object for the object <em>ob</em>. This will always return
a new reference, but is not guaranteed to create a new object; an existing
reference object may be returned. The second parameter, <em>callback</em>, can be a
callable object that receives notification when <em>ob</em> is garbage collected; it
should accept a single parameter, which will be the weak reference object
itself. <em>callback</em> may also be <code class="docutils literal notranslate"><span class="pre">None</span></code> or <code class="docutils literal notranslate"><span class="pre">NULL</span></code>. If <em>ob</em> is not a
weakly referencable object, or if <em>callback</em> is not callable, <code class="docutils literal notranslate"><span class="pre">None</span></code>, or
<code class="docutils literal notranslate"><span class="pre">NULL</span></code>, this will return <code class="docutils literal notranslate"><span class="pre">NULL</span></code> and raise <a class="reference internal" href="../library/exceptions.html#TypeError" title="TypeError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">TypeError</span></code></a>.</p>
</dd></dl>
<dl class="c function">
<dt class="sig sig-object c" id="c.PyWeakref_NewProxy">
<a class="reference internal" href="structures.html#c.PyObject" title="PyObject"><span class="n"><span class="pre">PyObject</span></span></a><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="sig-name descname"><span class="n"><span class="pre">PyWeakref_NewProxy</span></span></span><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject"><span class="n"><span class="pre">PyObject</span></span></a><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">ob</span></span>, <a class="reference internal" href="structures.html#c.PyObject" title="PyObject"><span class="n"><span class="pre">PyObject</span></span></a><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">callback</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.PyWeakref_NewProxy" title="Permalink to this definition"></a><br /></dt>
<dd><em class="refcount">Return value: New reference.</em><em class="stableabi"> Part of the <a class="reference internal" href="stable.html#stable"><span class="std std-ref">Stable ABI</span></a>.</em><p>Return a weak reference proxy object for the object <em>ob</em>. This will always
return a new reference, but is not guaranteed to create a new object; an
existing proxy object may be returned. The second parameter, <em>callback</em>, can
be a callable object that receives notification when <em>ob</em> is garbage
collected; it should accept a single parameter, which will be the weak
reference object itself. <em>callback</em> may also be <code class="docutils literal notranslate"><span class="pre">None</span></code> or <code class="docutils literal notranslate"><span class="pre">NULL</span></code>. If <em>ob</em>
is not a weakly referencable object, or if <em>callback</em> is not callable,
<code class="docutils literal notranslate"><span class="pre">None</span></code>, or <code class="docutils literal notranslate"><span class="pre">NULL</span></code>, this will return <code class="docutils literal notranslate"><span class="pre">NULL</span></code> and raise <a class="reference internal" href="../library/exceptions.html#TypeError" title="TypeError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">TypeError</span></code></a>.</p>
</dd></dl>
<dl class="c function">
<dt class="sig sig-object c" id="c.PyWeakref_GetObject">
<a class="reference internal" href="structures.html#c.PyObject" title="PyObject"><span class="n"><span class="pre">PyObject</span></span></a><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="sig-name descname"><span class="n"><span class="pre">PyWeakref_GetObject</span></span></span><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject"><span class="n"><span class="pre">PyObject</span></span></a><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">ref</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.PyWeakref_GetObject" title="Permalink to this definition"></a><br /></dt>
<dd><em class="refcount">Return value: Borrowed reference.</em><em class="stableabi"> Part of the <a class="reference internal" href="stable.html#stable"><span class="std std-ref">Stable ABI</span></a>.</em><p>Return the referenced object from a weak reference, <em>ref</em>. If the referent is
no longer live, returns <code class="docutils literal notranslate"><span class="pre">Py_None</span></code>.</p>
<div class="admonition note">
<p class="admonition-title">Note</p>
<p>This function returns a <a class="reference internal" href="../glossary.html#term-borrowed-reference"><span class="xref std std-term">borrowed reference</span></a> to the referenced object.
This means that you should always call <a class="reference internal" href="refcounting.html#c.Py_INCREF" title="Py_INCREF"><code class="xref c c-func docutils literal notranslate"><span class="pre">Py_INCREF()</span></code></a> on the object
except when it cannot be destroyed before the last usage of the borrowed
reference.</p>
</div>
</dd></dl>
<dl class="c function">
<dt class="sig sig-object c" id="c.PyWeakref_GET_OBJECT">
<a class="reference internal" href="structures.html#c.PyObject" title="PyObject"><span class="n"><span class="pre">PyObject</span></span></a><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="sig-name descname"><span class="n"><span class="pre">PyWeakref_GET_OBJECT</span></span></span><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject"><span class="n"><span class="pre">PyObject</span></span></a><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">ref</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.PyWeakref_GET_OBJECT" title="Permalink to this definition"></a><br /></dt>
<dd><em class="refcount">Return value: Borrowed reference.</em><p>Similar to <a class="reference internal" href="#c.PyWeakref_GetObject" title="PyWeakref_GetObject"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyWeakref_GetObject()</span></code></a>, but does no error checking.</p>
</dd></dl>
<dl class="c function">
<dt class="sig sig-object c" id="c.PyObject_ClearWeakRefs">
<span class="kt"><span class="pre">void</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">PyObject_ClearWeakRefs</span></span></span><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject"><span class="n"><span class="pre">PyObject</span></span></a><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">object</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.PyObject_ClearWeakRefs" title="Permalink to this definition"></a><br /></dt>
<dd><em class="stableabi"> Part of the <a class="reference internal" href="stable.html#stable"><span class="std std-ref">Stable ABI</span></a>.</em><p>This function is called by the <a class="reference internal" href="typeobj.html#c.PyTypeObject.tp_dealloc" title="PyTypeObject.tp_dealloc"><code class="xref c c-member docutils literal notranslate"><span class="pre">tp_dealloc</span></code></a> handler
to clear weak references.</p>
<p>This iterates through the weak references for <em>object</em> and calls callbacks
for those references which have one. It returns when all callbacks have
been attempted.</p>
</dd></dl>
</section>
<div class="clearer"></div>
</div>
</div>
</div>
<div class="sphinxsidebar" role="navigation" aria-label="main navigation">
<div class="sphinxsidebarwrapper">
<div>
<h4>Previous topic</h4>
<p class="topless"><a href="memoryview.html"
title="previous chapter">MemoryView objects</a></p>
</div>
<div>
<h4>Next topic</h4>
<p class="topless"><a href="capsule.html"
title="next chapter">Capsules</a></p>
</div>
<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/main/Doc/c-api/weakref.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="capsule.html" title="Capsules"
>next</a> |</li>
<li class="right" >
<a href="memoryview.html" title="MemoryView objects"
>previous</a> |</li>
<li><img src="../_static/py.svg" alt="python logo" style="vertical-align: middle; margin-top: -1px"/></li>
<li><a href="https://www.python.org/">Python</a> &#187;</li>
<li class="switchers">
<div class="language_switcher_placeholder"></div>
<div class="version_switcher_placeholder"></div>
</li>
<li>
</li>
<li id="cpython-language-and-version">
<a href="../index.html">3.12.0 Documentation</a> &#187;
</li>
<li class="nav-item nav-item-1"><a href="index.html" >Python/C API Reference Manual</a> &#187;</li>
<li class="nav-item nav-item-2"><a href="concrete.html" >Concrete Objects Layer</a> &#187;</li>
<li class="nav-item nav-item-this"><a href="">Weak Reference Objects</a></li>
<li class="right">
<div class="inline-search" role="search">
<form class="inline-search" action="../search.html" method="get">
<input placeholder="Quick search" aria-label="Quick search" type="search" name="q" />
<input type="submit" value="Go" />
</form>
</div>
|
</li>
<li class="right">
<label class="theme-selector-label">
Theme
<select class="theme-selector" oninput="activateTheme(this.value)">
<option value="auto" selected>Auto</option>
<option value="light">Light</option>
<option value="dark">Dark</option>
</select>
</label> |</li>
</ul>
</div>
<div class="footer">
&copy; <a href="../copyright.html">Copyright</a> 2001-2023, Python Software Foundation.
<br />
This page is licensed under the Python Software Foundation License Version 2.
<br />
Examples, recipes, and other code in the documentation are additionally licensed under the Zero Clause BSD License.
<br />
See <a href="/license.html">History and License</a> for more information.<br />
<br />
The Python Software Foundation is a non-profit corporation.
<a href="https://www.python.org/psf/donations/">Please donate.</a>
<br />
<br />
Last updated on Oct 02, 2023.
<a href="/bugs.html">Found a bug</a>?
<br />
Created using <a href="https://www.sphinx-doc.org/">Sphinx</a> 4.5.0.
</div>
</body>
</html>
Reference in New Issue View Git Blame Copy Permalink