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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="X-UA-Compatible" content="IE=Edge" /> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>Allocating Objects on the Heap — Python 2.7.16 documentation</title> <link rel="stylesheet" href="../_static/classic.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/sidebar.js"></script> <link rel="search" type="application/opensearchdescription+xml" title="Search within Python 2.7.16 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="Common Object Structures" href="structures.html" /> <link rel="prev" title="Object Implementation Support" href="objimpl.html" /> <link rel="shortcut icon" type="image/png" href="../_static/py.png" /> <link rel="canonical" href="https://docs.python.org/2/c-api/allocation.html" /> <script type="text/javascript" src="../_static/copybutton.js"></script> </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="structures.html" title="Common Object Structures" accesskey="N">next</a> |</li> <li class="right" > <a href="objimpl.html" title="Object Implementation Support" 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> <a href="../index.html">Python 2.7.16 documentation</a> » </li> <li class="nav-item nav-item-1"><a href="index.html" >Python/C API Reference Manual</a> »</li> <li class="nav-item nav-item-2"><a href="objimpl.html" accesskey="U">Object Implementation Support</a> »</li> </ul> </div> <div class="document"> <div class="documentwrapper"> <div class="bodywrapper"> <div class="body" role="main"> <div class="section" id="allocating-objects-on-the-heap"> <span id="allocating-objects"></span><h1>Allocating Objects on the Heap<a class="headerlink" href="#allocating-objects-on-the-heap" title="Permalink to this headline">¶</a></h1> <dl class="function"> <dt id="c._PyObject_New"> <a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a>* <code class="descname">_PyObject_New</code><span class="sig-paren">(</span><a class="reference internal" href="type.html#c.PyTypeObject" title="PyTypeObject">PyTypeObject</a><em> *type</em><span class="sig-paren">)</span><a class="headerlink" href="#c._PyObject_New" title="Permalink to this definition">¶</a></dt> <dd><em class="refcount">Return value: New reference.</em></dd></dl> <dl class="function"> <dt id="c._PyObject_NewVar"> <a class="reference internal" href="structures.html#c.PyVarObject" title="PyVarObject">PyVarObject</a>* <code class="descname">_PyObject_NewVar</code><span class="sig-paren">(</span><a class="reference internal" href="type.html#c.PyTypeObject" title="PyTypeObject">PyTypeObject</a><em> *type</em>, Py_ssize_t<em> size</em><span class="sig-paren">)</span><a class="headerlink" href="#c._PyObject_NewVar" title="Permalink to this definition">¶</a></dt> <dd><em class="refcount">Return value: New reference.</em><div class="versionchanged"> <p><span class="versionmodified">Changed in version 2.5: </span>This function used an <code class="xref c c-type docutils literal notranslate"><span class="pre">int</span></code> type for <em>size</em>. This might require changes in your code for properly supporting 64-bit systems.</p> </div> </dd></dl> <dl class="function"> <dt id="c._PyObject_Del"> void <code class="descname">_PyObject_Del</code><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a><em> *op</em><span class="sig-paren">)</span><a class="headerlink" href="#c._PyObject_Del" title="Permalink to this definition">¶</a></dt> <dd></dd></dl> <dl class="function"> <dt id="c.PyObject_Init"> <a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a>* <code class="descname">PyObject_Init</code><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a><em> *op</em>, <a class="reference internal" href="type.html#c.PyTypeObject" title="PyTypeObject">PyTypeObject</a><em> *type</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyObject_Init" title="Permalink to this definition">¶</a></dt> <dd><em class="refcount">Return value: Borrowed reference.</em><p>Initialize a newly-allocated object <em>op</em> with its type and initial reference. Returns the initialized object. If <em>type</em> indicates that the object participates in the cyclic garbage detector, it is added to the detector’s set of observed objects. Other fields of the object are not affected.</p> </dd></dl> <dl class="function"> <dt id="c.PyObject_InitVar"> <a class="reference internal" href="structures.html#c.PyVarObject" title="PyVarObject">PyVarObject</a>* <code class="descname">PyObject_InitVar</code><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyVarObject" title="PyVarObject">PyVarObject</a><em> *op</em>, <a class="reference internal" href="type.html#c.PyTypeObject" title="PyTypeObject">PyTypeObject</a><em> *type</em>, Py_ssize_t<em> size</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyObject_InitVar" title="Permalink to this definition">¶</a></dt> <dd><em class="refcount">Return value: Borrowed reference.</em><p>This does everything <a class="reference internal" href="#c.PyObject_Init" title="PyObject_Init"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyObject_Init()</span></code></a> does, and also initializes the length information for a variable-size object.</p> <div class="versionchanged"> <p><span class="versionmodified">Changed in version 2.5: </span>This function used an <code class="xref c c-type docutils literal notranslate"><span class="pre">int</span></code> type for <em>size</em>. This might require changes in your code for properly supporting 64-bit systems.</p> </div> </dd></dl> <dl class="function"> <dt id="c.PyObject_New"> TYPE* <code class="descname">PyObject_New</code><span class="sig-paren">(</span>TYPE, <a class="reference internal" href="type.html#c.PyTypeObject" title="PyTypeObject">PyTypeObject</a><em> *type</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyObject_New" title="Permalink to this definition">¶</a></dt> <dd><em class="refcount">Return value: New reference.</em><p>Allocate a new Python object using the C structure type <em>TYPE</em> and the Python type object <em>type</em>. Fields not defined by the Python object header are not initialized; the object’s reference count will be one. The size of the memory allocation is determined from the <a class="reference internal" href="typeobj.html#c.PyTypeObject.tp_basicsize" title="PyTypeObject.tp_basicsize"><code class="xref c c-member docutils literal notranslate"><span class="pre">tp_basicsize</span></code></a> field of the type object.</p> </dd></dl> <dl class="function"> <dt id="c.PyObject_NewVar"> TYPE* <code class="descname">PyObject_NewVar</code><span class="sig-paren">(</span>TYPE, <a class="reference internal" href="type.html#c.PyTypeObject" title="PyTypeObject">PyTypeObject</a><em> *type</em>, Py_ssize_t<em> size</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyObject_NewVar" title="Permalink to this definition">¶</a></dt> <dd><em class="refcount">Return value: New reference.</em><p>Allocate a new Python object using the C structure type <em>TYPE</em> and the Python type object <em>type</em>. Fields not defined by the Python object header are not initialized. The allocated memory allows for the <em>TYPE</em> structure plus <em>size</em> fields of the size given by the <a class="reference internal" href="typeobj.html#c.PyTypeObject.tp_itemsize" title="PyTypeObject.tp_itemsize"><code class="xref c c-member docutils literal notranslate"><span class="pre">tp_itemsize</span></code></a> field of <em>type</em>. This is useful for implementing objects like tuples, which are able to determine their size at construction time. Embedding the array of fields into the same allocation decreases the number of allocations, improving the memory management efficiency.</p> <div class="versionchanged"> <p><span class="versionmodified">Changed in version 2.5: </span>This function used an <code class="xref c c-type docutils literal notranslate"><span class="pre">int</span></code> type for <em>size</em>. This might require changes in your code for properly supporting 64-bit systems.</p> </div> </dd></dl> <dl class="function"> <dt id="c.PyObject_Del"> void <code class="descname">PyObject_Del</code><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a><em> *op</em><span class="sig-paren">)</span><a class="headerlink" href="#c.PyObject_Del" title="Permalink to this definition">¶</a></dt> <dd><p>Releases memory allocated to an object using <a class="reference internal" href="#c.PyObject_New" title="PyObject_New"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyObject_New()</span></code></a> or <a class="reference internal" href="#c.PyObject_NewVar" title="PyObject_NewVar"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyObject_NewVar()</span></code></a>. This is normally called from 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 specified in the object’s type. The fields of the object should not be accessed after this call as the memory is no longer a valid Python object.</p> </dd></dl> <dl class="function"> <dt id="c.Py_InitModule"> <a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a>* <code class="descname">Py_InitModule</code><span class="sig-paren">(</span>char<em> *name</em>, <a class="reference internal" href="structures.html#c.PyMethodDef" title="PyMethodDef">PyMethodDef</a><em> *methods</em><span class="sig-paren">)</span><a class="headerlink" href="#c.Py_InitModule" title="Permalink to this definition">¶</a></dt> <dd><em class="refcount">Return value: Borrowed reference.</em><p>Create a new module object based on a name and table of functions, returning the new module object.</p> <div class="versionchanged"> <p><span class="versionmodified">Changed in version 2.3: </span>Older versions of Python did not support <em>NULL</em> as the value for the <em>methods</em> argument.</p> </div> </dd></dl> <dl class="function"> <dt id="c.Py_InitModule3"> <a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a>* <code class="descname">Py_InitModule3</code><span class="sig-paren">(</span>char<em> *name</em>, <a class="reference internal" href="structures.html#c.PyMethodDef" title="PyMethodDef">PyMethodDef</a><em> *methods</em>, char<em> *doc</em><span class="sig-paren">)</span><a class="headerlink" href="#c.Py_InitModule3" title="Permalink to this definition">¶</a></dt> <dd><em class="refcount">Return value: Borrowed reference.</em><p>Create a new module object based on a name and table of functions, returning the new module object. If <em>doc</em> is non-<em>NULL</em>, it will be used to define the docstring for the module.</p> <div class="versionchanged"> <p><span class="versionmodified">Changed in version 2.3: </span>Older versions of Python did not support <em>NULL</em> as the value for the <em>methods</em> argument.</p> </div> </dd></dl> <dl class="function"> <dt id="c.Py_InitModule4"> <a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a>* <code class="descname">Py_InitModule4</code><span class="sig-paren">(</span>char<em> *name</em>, <a class="reference internal" href="structures.html#c.PyMethodDef" title="PyMethodDef">PyMethodDef</a><em> *methods</em>, char<em> *doc</em>, <a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a><em> *self</em>, int<em> apiver</em><span class="sig-paren">)</span><a class="headerlink" href="#c.Py_InitModule4" title="Permalink to this definition">¶</a></dt> <dd><em class="refcount">Return value: Borrowed reference.</em><p>Create a new module object based on a name and table of functions, returning the new module object. If <em>doc</em> is non-<em>NULL</em>, it will be used to define the docstring for the module. If <em>self</em> is non-<em>NULL</em>, it will be passed to the functions of the module as their (otherwise <em>NULL</em>) first parameter. (This was added as an experimental feature, and there are no known uses in the current version of Python.) For <em>apiver</em>, the only value which should be passed is defined by the constant <code class="xref py py-const docutils literal notranslate"><span class="pre">PYTHON_API_VERSION</span></code>.</p> <div class="admonition note"> <p class="first admonition-title">Note</p> <p class="last">Most uses of this function should probably be using the <a class="reference internal" href="#c.Py_InitModule3" title="Py_InitModule3"><code class="xref c c-func docutils literal notranslate"><span class="pre">Py_InitModule3()</span></code></a> instead; only use this if you are sure you need it.</p> </div> <div class="versionchanged"> <p><span class="versionmodified">Changed in version 2.3: </span>Older versions of Python did not support <em>NULL</em> as the value for the <em>methods</em> argument.</p> </div> </dd></dl> <dl class="var"> <dt id="c._Py_NoneStruct"> <a class="reference internal" href="structures.html#c.PyObject" title="PyObject">PyObject</a> <code class="descname">_Py_NoneStruct</code><a class="headerlink" href="#c._Py_NoneStruct" title="Permalink to this definition">¶</a></dt> <dd><p>Object which is visible in Python as <code class="docutils literal notranslate"><span class="pre">None</span></code>. This should only be accessed using the <code class="docutils literal notranslate"><span class="pre">Py_None</span></code> macro, which evaluates to a pointer to this object.</p> </dd></dl> </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="objimpl.html" title="previous chapter">Object Implementation Support</a></p> <h4>Next topic</h4> <p class="topless"><a href="structures.html" title="next chapter">Common Object Structures</a></p> <div role="note" aria-label="source link"> <h3>This Page</h3> <ul class="this-page-menu"> <li><a href="../_sources/c-api/allocation.rst.txt" rel="nofollow">Show Source</a></li> </ul> </div> <div id="searchbox" style="display: none" role="search"> <h3>Quick search</h3> <div class="searchformwrapper"> <form class="search" action="../search.html" method="get"> <input 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> </div> <script type="text/javascript">$('#searchbox').show(0);</script> </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="structures.html" title="Common Object Structures" >next</a> |</li> <li class="right" > <a href="objimpl.html" title="Object Implementation Support" >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> <a href="../index.html">Python 2.7.16 documentation</a> » </li> <li class="nav-item nav-item-1"><a href="index.html" >Python/C API Reference Manual</a> »</li> <li class="nav-item nav-item-2"><a href="objimpl.html" >Object Implementation Support</a> »</li> </ul> </div> <div class="footer"> © <a href="../copyright.html">Copyright</a> 1990-2019, 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 Mar 27, 2019. <a href="../bugs.html">Found a bug</a>? <br /> Created using <a href="http://sphinx.pocoo.org/">Sphinx</a> 1.7.6. </div> </body> </html>