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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="Content-Type" content="text/html; charset=utf-8" /> <title>Allocating Objects on the Heap — Python 2.7.5 documentation</title> <link rel="stylesheet" href="../_static/default.css" type="text/css" /> <link rel="stylesheet" href="../_static/pygments.css" type="text/css" /> <script type="text/javascript"> var DOCUMENTATION_OPTIONS = { URL_ROOT: '../', VERSION: '2.7.5', COLLAPSE_INDEX: false, FILE_SUFFIX: '.html', HAS_SOURCE: true }; </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 2.7.5 documentation" href="../_static/opensearch.xml"/> <link rel="author" title="About these documents" href="../about.html" /> <link rel="copyright" title="Copyright" href="../copyright.html" /> <link rel="top" title="Python 2.7.5 documentation" href="../index.html" /> <link rel="up" title="Object Implementation Support" href="objimpl.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" /> <script type="text/javascript" src="../_static/copybutton.js"></script> </head> <body> <div class="related"> <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="http://www.python.org/">Python</a> »</li> <li> <a href="../index.html">Python 2.7.5 documentation</a> » </li> <li><a href="index.html" >Python/C API Reference Manual</a> »</li> <li><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"> <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="_PyObject_New"> <a class="reference internal" href="structures.html#PyObject" title="PyObject">PyObject</a>* <tt class="descname">_PyObject_New</tt><big>(</big><a class="reference internal" href="type.html#PyTypeObject" title="PyTypeObject">PyTypeObject</a><em> *type</em><big>)</big><a class="headerlink" href="#_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="_PyObject_NewVar"> <a class="reference internal" href="structures.html#PyVarObject" title="PyVarObject">PyVarObject</a>* <tt class="descname">_PyObject_NewVar</tt><big>(</big><a class="reference internal" href="type.html#PyTypeObject" title="PyTypeObject">PyTypeObject</a><em> *type</em>, Py_ssize_t<em> size</em><big>)</big><a class="headerlink" href="#_PyObject_NewVar" title="Permalink to this definition">¶</a></dt> <dd><em class="refcount">Return value: New reference.</em><p class="versionchanged"> <span class="versionmodified">Changed in version 2.5: </span>This function used an <tt class="xref c c-type docutils literal"><span class="pre">int</span></tt> type for <em>size</em>. This might require changes in your code for properly supporting 64-bit systems.</p> </dd></dl> <dl class="function"> <dt id="_PyObject_Del"> void <tt class="descname">_PyObject_Del</tt><big>(</big><a class="reference internal" href="structures.html#PyObject" title="PyObject">PyObject</a><em> *op</em><big>)</big><a class="headerlink" href="#_PyObject_Del" title="Permalink to this definition">¶</a></dt> <dd></dd></dl> <dl class="function"> <dt id="PyObject_Init"> <a class="reference internal" href="structures.html#PyObject" title="PyObject">PyObject</a>* <tt class="descname">PyObject_Init</tt><big>(</big><a class="reference internal" href="structures.html#PyObject" title="PyObject">PyObject</a><em> *op</em>, <a class="reference internal" href="type.html#PyTypeObject" title="PyTypeObject">PyTypeObject</a><em> *type</em><big>)</big><a class="headerlink" href="#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="PyObject_InitVar"> <a class="reference internal" href="structures.html#PyVarObject" title="PyVarObject">PyVarObject</a>* <tt class="descname">PyObject_InitVar</tt><big>(</big><a class="reference internal" href="structures.html#PyVarObject" title="PyVarObject">PyVarObject</a><em> *op</em>, <a class="reference internal" href="type.html#PyTypeObject" title="PyTypeObject">PyTypeObject</a><em> *type</em>, Py_ssize_t<em> size</em><big>)</big><a class="headerlink" href="#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="#PyObject_Init" title="PyObject_Init"><tt class="xref c c-func docutils literal"><span class="pre">PyObject_Init()</span></tt></a> does, and also initializes the length information for a variable-size object.</p> <p class="versionchanged"> <span class="versionmodified">Changed in version 2.5: </span>This function used an <tt class="xref c c-type docutils literal"><span class="pre">int</span></tt> type for <em>size</em>. This might require changes in your code for properly supporting 64-bit systems.</p> </dd></dl> <dl class="function"> <dt id="PyObject_New"> TYPE* <tt class="descname">PyObject_New</tt><big>(</big>TYPE, <a class="reference internal" href="type.html#PyTypeObject" title="PyTypeObject">PyTypeObject</a><em> *type</em><big>)</big><a class="headerlink" href="#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 <tt class="xref py py-attr docutils literal"><span class="pre">tp_basicsize</span></tt> field of the type object.</p> </dd></dl> <dl class="function"> <dt id="PyObject_NewVar"> TYPE* <tt class="descname">PyObject_NewVar</tt><big>(</big>TYPE, <a class="reference internal" href="type.html#PyTypeObject" title="PyTypeObject">PyTypeObject</a><em> *type</em>, Py_ssize_t<em> size</em><big>)</big><a class="headerlink" href="#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 <tt class="xref py py-attr docutils literal"><span class="pre">tp_itemsize</span></tt> 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> <p class="versionchanged"> <span class="versionmodified">Changed in version 2.5: </span>This function used an <tt class="xref c c-type docutils literal"><span class="pre">int</span></tt> type for <em>size</em>. This might require changes in your code for properly supporting 64-bit systems.</p> </dd></dl> <dl class="function"> <dt id="PyObject_Del"> void <tt class="descname">PyObject_Del</tt><big>(</big><a class="reference internal" href="structures.html#PyObject" title="PyObject">PyObject</a><em> *op</em><big>)</big><a class="headerlink" href="#PyObject_Del" title="Permalink to this definition">¶</a></dt> <dd><p>Releases memory allocated to an object using <a class="reference internal" href="#PyObject_New" title="PyObject_New"><tt class="xref c c-func docutils literal"><span class="pre">PyObject_New()</span></tt></a> or <a class="reference internal" href="#PyObject_NewVar" title="PyObject_NewVar"><tt class="xref c c-func docutils literal"><span class="pre">PyObject_NewVar()</span></tt></a>. This is normally called from the <tt class="xref py py-attr docutils literal"><span class="pre">tp_dealloc</span></tt> 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="Py_InitModule"> <a class="reference internal" href="structures.html#PyObject" title="PyObject">PyObject</a>* <tt class="descname">Py_InitModule</tt><big>(</big>char<em> *name</em>, <a class="reference internal" href="structures.html#PyMethodDef" title="PyMethodDef">PyMethodDef</a><em> *methods</em><big>)</big><a class="headerlink" href="#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> <p class="versionchanged"> <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> </dd></dl> <dl class="function"> <dt id="Py_InitModule3"> <a class="reference internal" href="structures.html#PyObject" title="PyObject">PyObject</a>* <tt class="descname">Py_InitModule3</tt><big>(</big>char<em> *name</em>, <a class="reference internal" href="structures.html#PyMethodDef" title="PyMethodDef">PyMethodDef</a><em> *methods</em>, char<em> *doc</em><big>)</big><a class="headerlink" href="#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> <p class="versionchanged"> <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> </dd></dl> <dl class="function"> <dt id="Py_InitModule4"> <a class="reference internal" href="structures.html#PyObject" title="PyObject">PyObject</a>* <tt class="descname">Py_InitModule4</tt><big>(</big>char<em> *name</em>, <a class="reference internal" href="structures.html#PyMethodDef" title="PyMethodDef">PyMethodDef</a><em> *methods</em>, char<em> *doc</em>, <a class="reference internal" href="structures.html#PyObject" title="PyObject">PyObject</a><em> *self</em>, int<em> apiver</em><big>)</big><a class="headerlink" href="#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 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 <tt class="xref py py-const docutils literal"><span class="pre">PYTHON_API_VERSION</span></tt>.</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="#Py_InitModule3" title="Py_InitModule3"><tt class="xref c c-func docutils literal"><span class="pre">Py_InitModule3()</span></tt></a> instead; only use this if you are sure you need it.</p> </div> <p class="versionchanged"> <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> </dd></dl> <dl class="var"> <dt id="_Py_NoneStruct"> <a class="reference internal" href="structures.html#PyObject" title="PyObject">PyObject</a> <tt class="descname">_Py_NoneStruct</tt><a class="headerlink" href="#_Py_NoneStruct" title="Permalink to this definition">¶</a></dt> <dd><p>Object which is visible in Python as <tt class="docutils literal"><span class="pre">None</span></tt>. This should only be accessed using the <tt class="docutils literal"><span class="pre">Py_None</span></tt> macro, which evaluates to a pointer to this object.</p> </dd></dl> </div> </div> </div> </div> <div class="sphinxsidebar"> <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> <h3>This Page</h3> <ul class="this-page-menu"> <li><a href="../bugs.html">Report a Bug</a></li> <li><a href="../_sources/c-api/allocation.txt" rel="nofollow">Show Source</a></li> </ul> <div id="searchbox" style="display: none"> <h3>Quick search</h3> <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> <p class="searchtip" style="font-size: 90%"> Enter search terms or a module, class or function name. </p> </div> <script type="text/javascript">$('#searchbox').show(0);</script> </div> </div> <div class="clearer"></div> </div> <div class="related"> <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="http://www.python.org/">Python</a> »</li> <li> <a href="../index.html">Python 2.7.5 documentation</a> » </li> <li><a href="index.html" >Python/C API Reference Manual</a> »</li> <li><a href="objimpl.html" >Object Implementation Support</a> »</li> </ul> </div> <div class="footer"> © <a href="../copyright.html">Copyright</a> 1990-2020, Python Software Foundation. <br /> The Python Software Foundation is a non-profit corporation. <a href="http://www.python.org/psf/donations/">Please donate.</a> <br /> Last updated on Oct 13, 2020. <a href="../bugs.html">Found a bug</a>? <br /> Created using <a href="http://sphinx.pocoo.org/">Sphinx</a> 1.1.3. </div> </body> </html>