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  <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="c function">
<dt class="sig sig-object c" id="c._PyObject_New">
<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">_PyObject_New</span></span></span><span class="sig-paren">(</span><a class="reference internal" href="type.html#c.PyTypeObject" title="PyTypeObject"><span class="n"><span class="pre">PyTypeObject</span></span></a><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">type</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c._PyObject_New" title="Permalink to this definition">¶</a><br /></dt>
<dd><em class="refcount">Return value: New reference.</em></dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c._PyObject_NewVar">
<a class="reference internal" href="structures.html#c.PyVarObject" title="PyVarObject"><span class="n"><span class="pre">PyVarObject</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">_PyObject_NewVar</span></span></span><span class="sig-paren">(</span><a class="reference internal" href="type.html#c.PyTypeObject" title="PyTypeObject"><span class="n"><span class="pre">PyTypeObject</span></span></a><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">type</span></span>, <a class="reference internal" href="intro.html#c.Py_ssize_t" title="Py_ssize_t"><span class="n"><span class="pre">Py_ssize_t</span></span></a><span class="w"> </span><span class="n"><span class="pre">size</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c._PyObject_NewVar" title="Permalink to this definition">¶</a><br /></dt>
<dd><em class="refcount">Return value: New reference.</em></dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PyObject_Init">
<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">PyObject_Init</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">op</span></span>, <a class="reference internal" href="type.html#c.PyTypeObject" title="PyTypeObject"><span class="n"><span class="pre">PyTypeObject</span></span></a><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">type</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.PyObject_Init" 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>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="c function">
<dt class="sig sig-object c" id="c.PyObject_InitVar">
<a class="reference internal" href="structures.html#c.PyVarObject" title="PyVarObject"><span class="n"><span class="pre">PyVarObject</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">PyObject_InitVar</span></span></span><span class="sig-paren">(</span><a class="reference internal" href="structures.html#c.PyVarObject" title="PyVarObject"><span class="n"><span class="pre">PyVarObject</span></span></a><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">op</span></span>, <a class="reference internal" href="type.html#c.PyTypeObject" title="PyTypeObject"><span class="n"><span class="pre">PyTypeObject</span></span></a><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">type</span></span>, <a class="reference internal" href="intro.html#c.Py_ssize_t" title="Py_ssize_t"><span class="n"><span class="pre">Py_ssize_t</span></span></a><span class="w"> </span><span class="n"><span class="pre">size</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.PyObject_InitVar" 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>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>
</dd></dl>

<dl class="c macro">
<dt class="sig sig-object c" id="c.PyObject_New">
<span class="sig-name descname"><span class="n"><span class="pre">PyObject_New</span></span></span><span class="sig-paren">(</span><span class="n"><span class="pre">TYPE</span></span>, <span class="n"><span class="pre">typeobj</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.PyObject_New" title="Permalink to this definition">¶</a><br /></dt>
<dd><p>Allocate a new Python object using the C structure type <em>TYPE</em>
and the Python type object <em>typeobj</em> (<code class="docutils literal notranslate"><span class="pre">PyTypeObject*</span></code>).
Fields not defined by the Python object header are not initialized.
The caller will own the only reference to the object
(i.e. its 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="c macro">
<dt class="sig sig-object c" id="c.PyObject_NewVar">
<span class="sig-name descname"><span class="n"><span class="pre">PyObject_NewVar</span></span></span><span class="sig-paren">(</span><span class="n"><span class="pre">TYPE</span></span>, <span class="n"><span class="pre">typeobj</span></span>, <span class="n"><span class="pre">size</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.PyObject_NewVar" title="Permalink to this definition">¶</a><br /></dt>
<dd><p>Allocate a new Python object using the C structure type <em>TYPE</em> and the
Python type object <em>typeobj</em> (<code class="docutils literal notranslate"><span class="pre">PyTypeObject*</span></code>).
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> (<code class="docutils literal notranslate"><span class="pre">Py_ssize_t</span></code>) 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>typeobj</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>
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.PyObject_Del">
<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_Del</span></span></span><span class="sig-paren">(</span><span class="kt"><span class="pre">void</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">op</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.PyObject_Del" title="Permalink to this definition">¶</a><br /></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-macro 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-macro 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="c var">
<dt class="sig sig-object c" id="c._Py_NoneStruct">
<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="sig-name descname"><span class="n"><span class="pre">_Py_NoneStruct</span></span></span><a class="headerlink" href="#c._Py_NoneStruct" title="Permalink to this definition">¶</a><br /></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 <a class="reference internal" href="none.html#c.Py_None" title="Py_None"><code class="xref c c-macro docutils literal notranslate"><span class="pre">Py_None</span></code></a> macro, which evaluates to a pointer to this
object.</p>
</dd></dl>

<div class="admonition seealso">
<p class="admonition-title">See also</p>
<dl class="simple">
<dt><a class="reference internal" href="module.html#c.PyModule_Create" title="PyModule_Create"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyModule_Create()</span></code></a></dt><dd><p>To allocate and create extension modules.</p>
</dd>
</dl>
</div>
</section>


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