0x1949 Team - FAZEMRX - MANAGER

Edit File: structures.html

<!DOCTYPE html>

<title>Common Object Structures &#8212; Python 2.7.18 documentation</title>
 <link rel="stylesheet" type="text/css" href="../_static/pygments.css" />
 <link rel="stylesheet" type="text/css" href="../_static/classic.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 2.7.18 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="Type Objects" href="typeobj.html" />
 <link rel="prev" title="Allocating Objects on the Heap" href="allocation.html" />
 <link rel="shortcut icon" type="image/png" href="../_static/py.png" />
 <link rel="canonical" href="file:///usr/share/doc/python2.7/html/c-api/structures.html" />
 <script type="text/javascript" src="../_static/copybutton.js"></script>

</head><body>
<div id="outdated-warning" style="padding: .5em; text-align: center; background-color: #FFBABA; color: #6A0E0E;">
 This document is for an old version of Python that is <a href="https://devguide.python.org/devcycle/#end-of-life-branches">no longer supported</a>.
 You should install the python3 and python3-doc packages and read the 
 <a href="file:///usr/share/doc/python3-doc/html/c-api/structures.html"> Python documentation for the Python3 version packaged in this release</a>.
</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="typeobj.html" title="Type Objects"
 accesskey="N">next</a> |</li>
 <li class="right" >
 <a href="allocation.html" title="Allocating Objects on the Heap"
 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> &#187;</li>
 <li>
 <a href="../index.html">Python 2.7.18 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="objimpl.html" accesskey="U">Object Implementation Support</a> &#187;</li>
 <li class="nav-item nav-item-this"><a href="">Common Object Structures</a></li> 
 </ul>
 </div>

<div class="document">
 <div class="documentwrapper">
 <div class="bodywrapper">
 <div class="body" role="main">
 
 <section id="common-object-structures">
<h1>Common Object Structures<a class="headerlink" href="#common-object-structures" title="Permalink to this headline">¶</a></h1>
There are a large number of structures which are used in the definition of
object types for Python. This section describes these structures and how they
are used.
All Python objects ultimately share a small number of fields at the beginning
of the object’s representation in memory. These are represented by the
<a class="reference internal" href="#c.PyObject" title="PyObject"><code class="xref c c-type docutils literal notranslate">PyObject</code></a> and <a class="reference internal" href="#c.PyVarObject" title="PyVarObject"><code class="xref c c-type docutils literal notranslate">PyVarObject</code></a> types, which are defined, in turn,
by the expansions of some macros also used, whether directly or indirectly, in
the definition of all other Python objects.
<dl class="c type">
<dt class="sig sig-object c" id="c.PyObject">
type PyObject<a class="headerlink" href="#c.PyObject" title="Permalink to this definition">¶</a> </dt>
<dd>All object types are extensions of this type. This is a type which
contains the information Python needs to treat a pointer to an object as an
object. In a normal “release” build, it contains only the object’s
reference count and a pointer to the corresponding type object. It
corresponds to the fields defined by the expansion of the <code class="docutils literal notranslate">PyObject_HEAD</code>
macro.
</dd></dl>

<dl class="c type">
<dt class="sig sig-object c" id="c.PyVarObject">
type PyVarObject<a class="headerlink" href="#c.PyVarObject" title="Permalink to this definition">¶</a> </dt>
<dd>This is an extension of <a class="reference internal" href="#c.PyObject" title="PyObject"><code class="xref c c-type docutils literal notranslate">PyObject</code></a> that adds the <code class="xref py py-attr docutils literal notranslate">ob_size</code>
field. This is only used for objects that have some notion of length.
This type does not often appear in the Python/C API. It corresponds to the
fields defined by the expansion of the <code class="docutils literal notranslate">PyObject_VAR_HEAD</code> macro.
</dd></dl>

These macros are used in the definition of <a class="reference internal" href="#c.PyObject" title="PyObject"><code class="xref c c-type docutils literal notranslate">PyObject</code></a> and
<a class="reference internal" href="#c.PyVarObject" title="PyVarObject"><code class="xref c c-type docutils literal notranslate">PyVarObject</code></a>:
<dl class="c macro">
<dt class="sig sig-object c" id="c.PyObject_HEAD">
PyObject_HEAD<a class="headerlink" href="#c.PyObject_HEAD" title="Permalink to this definition">¶</a> </dt>
<dd>This is a macro which expands to the declarations of the fields of the
<a class="reference internal" href="#c.PyObject" title="PyObject"><code class="xref c c-type docutils literal notranslate">PyObject</code></a> type; it is used when declaring new types which represent
objects without a varying length. The specific fields it expands to depend
on the definition of <code class="xref c c-macro docutils literal notranslate">Py_TRACE_REFS</code>. By default, that macro is
not defined, and <a class="reference internal" href="#c.PyObject_HEAD" title="PyObject_HEAD"><code class="xref c c-macro docutils literal notranslate">PyObject_HEAD</code></a> expands to:
<div class="highlight-default notranslate"><div class="highlight"><pre>Py_ssize_t ob_refcnt;
PyTypeObject *ob_type;
</pre></div>
</div>
When <code class="xref c c-macro docutils literal notranslate">Py_TRACE_REFS</code> is defined, it expands to:
<div class="highlight-default notranslate"><div class="highlight"><pre>PyObject *_ob_next, *_ob_prev;
Py_ssize_t ob_refcnt;
PyTypeObject *ob_type;
</pre></div>
</div>
</dd></dl>

<dl class="c macro">
<dt class="sig sig-object c" id="c.PyObject_VAR_HEAD">
PyObject_VAR_HEAD<a class="headerlink" href="#c.PyObject_VAR_HEAD" title="Permalink to this definition">¶</a> </dt>
<dd>This is a macro which expands to the declarations of the fields of the
<a class="reference internal" href="#c.PyVarObject" title="PyVarObject"><code class="xref c c-type docutils literal notranslate">PyVarObject</code></a> type; it is used when declaring new types which
represent objects with a length that varies from instance to instance.
This macro always expands to:
<div class="highlight-default notranslate"><div class="highlight"><pre>PyObject_HEAD
Py_ssize_t ob_size;
</pre></div>
</div>
Note that <a class="reference internal" href="#c.PyObject_HEAD" title="PyObject_HEAD"><code class="xref c c-macro docutils literal notranslate">PyObject_HEAD</code></a> is part of the expansion, and that its own
expansion varies depending on the definition of <code class="xref c c-macro docutils literal notranslate">Py_TRACE_REFS</code>.
</dd></dl>

<dl class="c macro">
<dt class="sig sig-object c" id="c.Py_TYPE">
Py_TYPE(o)<a class="headerlink" href="#c.Py_TYPE" title="Permalink to this definition">¶</a> </dt>
<dd>This macro is used to access the <code class="xref py py-attr docutils literal notranslate">ob_type</code> member of a Python object.
It expands to:
<div class="highlight-default notranslate"><div class="highlight"><pre>(((PyObject*)(o))-&gt;ob_type)
</pre></div>
</div>
<div class="versionadded">
New in version 2.6.
</div>
</dd></dl>

<dl class="c macro">
<dt class="sig sig-object c" id="c.Py_REFCNT">
Py_REFCNT(o)<a class="headerlink" href="#c.Py_REFCNT" title="Permalink to this definition">¶</a> </dt>
<dd>This macro is used to access the <code class="xref py py-attr docutils literal notranslate">ob_refcnt</code> member of a Python
object.
It expands to:
<div class="highlight-default notranslate"><div class="highlight"><pre>(((PyObject*)(o))-&gt;ob_refcnt)
</pre></div>
</div>
<div class="versionadded">
New in version 2.6.
</div>
</dd></dl>

<dl class="c macro">
<dt class="sig sig-object c" id="c.Py_SIZE">
Py_SIZE(o)<a class="headerlink" href="#c.Py_SIZE" title="Permalink to this definition">¶</a> </dt>
<dd>This macro is used to access the <code class="xref py py-attr docutils literal notranslate">ob_size</code> member of a Python object.
It expands to:
<div class="highlight-default notranslate"><div class="highlight"><pre>(((PyVarObject*)(o))-&gt;ob_size)
</pre></div>
</div>
<div class="versionadded">
New in version 2.6.
</div>
</dd></dl>

<dl class="c macro">
<dt class="sig sig-object c" id="c.PyObject_HEAD_INIT">
PyObject_HEAD_INIT(type)<a class="headerlink" href="#c.PyObject_HEAD_INIT" title="Permalink to this definition">¶</a> </dt>
<dd>This is a macro which expands to initialization values for a new
<a class="reference internal" href="#c.PyObject" title="PyObject"><code class="xref c c-type docutils literal notranslate">PyObject</code></a> type. This macro expands to:
<div class="highlight-default notranslate"><div class="highlight"><pre>_PyObject_EXTRA_INIT
1, type,
</pre></div>
</div>
</dd></dl>

<dl class="c macro">
<dt class="sig sig-object c" id="c.PyVarObject_HEAD_INIT">
PyVarObject_HEAD_INIT(type, size)<a class="headerlink" href="#c.PyVarObject_HEAD_INIT" title="Permalink to this definition">¶</a> </dt>
<dd>This is a macro which expands to initialization values for a new
<a class="reference internal" href="#c.PyVarObject" title="PyVarObject"><code class="xref c c-type docutils literal notranslate">PyVarObject</code></a> type, including the <code class="xref py py-attr docutils literal notranslate">ob_size</code> field.
This macro expands to:
<div class="highlight-default notranslate"><div class="highlight"><pre>_PyObject_EXTRA_INIT
1, type, size,
</pre></div>
</div>
</dd></dl>

<dl class="c type">
<dt class="sig sig-object c" id="c.PyCFunction">
type PyCFunction<a class="headerlink" href="#c.PyCFunction" title="Permalink to this definition">¶</a> </dt>
<dd>Type of the functions used to implement most Python callables in C.
Functions of this type take two <code class="xref c c-type docutils literal notranslate">PyObject*</code> parameters and return
one such value. If the return value is NULL, an exception shall have
been set. If not NULL, the return value is interpreted as the return
value of the function as exposed in Python. The function must return a new
reference.
</dd></dl>

<dl class="c type">
<dt class="sig sig-object c" id="c.PyMethodDef">
type PyMethodDef<a class="headerlink" href="#c.PyMethodDef" title="Permalink to this definition">¶</a> </dt>
<dd>Structure used to describe a method of an extension type. This structure has
four fields:
<table class="docutils align-default">
<colgroup>
<col style="width: 29%" />
<col style="width: 21%" />
<col style="width: 50%" />
</colgroup>
<thead>
<tr class="row-odd"><th class="head">Field</th>
<th class="head">C Type</th>
<th class="head">Meaning</th>
</tr>
</thead>
<tbody>
<tr class="row-even"><td><code class="xref py py-attr docutils literal notranslate">ml_name</code></td>
<td>char *</td>
<td>name of the method</td>
</tr>
<tr class="row-odd"><td><code class="xref py py-attr docutils literal notranslate">ml_meth</code></td>
<td>PyCFunction</td>
<td>pointer to the C
implementation</td>
</tr>
<tr class="row-even"><td><code class="xref py py-attr docutils literal notranslate">ml_flags</code></td>
<td>int</td>
<td>flag bits indicating how the
call should be constructed</td>
</tr>
<tr class="row-odd"><td><code class="xref py py-attr docutils literal notranslate">ml_doc</code></td>
<td>char *</td>
<td>points to the contents of the
docstring</td>
</tr>
</tbody>
</table>
</dd></dl>

The <code class="xref py py-attr docutils literal notranslate">ml_meth</code> is a C function pointer. The functions may be of different
types, but they always return <code class="xref c c-type docutils literal notranslate">PyObject*</code>. If the function is not of
the <a class="reference internal" href="#c.PyCFunction" title="PyCFunction"><code class="xref c c-type docutils literal notranslate">PyCFunction</code></a>, the compiler will require a cast in the method table.
Even though <a class="reference internal" href="#c.PyCFunction" title="PyCFunction"><code class="xref c c-type docutils literal notranslate">PyCFunction</code></a> defines the first parameter as
<code class="xref c c-type docutils literal notranslate">PyObject*</code>, it is common that the method implementation uses the
specific C type of the self object.
The <code class="xref py py-attr docutils literal notranslate">ml_flags</code> field is a bitfield which can include the following flags.
The individual flags indicate either a calling convention or a binding
convention. Of the calling convention flags, only <a class="reference internal" href="#METH_VARARGS" title="METH_VARARGS"><code class="xref py py-const docutils literal notranslate">METH_VARARGS</code></a> and
<a class="reference internal" href="#METH_KEYWORDS" title="METH_KEYWORDS"><code class="xref py py-const docutils literal notranslate">METH_KEYWORDS</code></a> can be combined. Any of the calling convention flags
can be combined with a binding flag.
<dl class="py data">
<dt class="sig sig-object py" id="METH_VARARGS">
METH_VARARGS<a class="headerlink" href="#METH_VARARGS" title="Permalink to this definition">¶</a></dt>
<dd>This is the typical calling convention, where the methods have the type
<a class="reference internal" href="#c.PyCFunction" title="PyCFunction"><code class="xref c c-type docutils literal notranslate">PyCFunction</code></a>. The function expects two <code class="xref c c-type docutils literal notranslate">PyObject*</code> values.
The first one is the self object for methods; for module functions, it is
the module object. The second parameter (often called args) is a tuple
object representing all arguments. This parameter is typically processed
using <a class="reference internal" href="arg.html#c.PyArg_ParseTuple" title="PyArg_ParseTuple"><code class="xref c c-func docutils literal notranslate">PyArg_ParseTuple()</code></a> or <a class="reference internal" href="arg.html#c.PyArg_UnpackTuple" title="PyArg_UnpackTuple"><code class="xref c c-func docutils literal notranslate">PyArg_UnpackTuple()</code></a>.
</dd></dl>

<dl class="py data">
<dt class="sig sig-object py" id="METH_KEYWORDS">
METH_KEYWORDS<a class="headerlink" href="#METH_KEYWORDS" title="Permalink to this definition">¶</a></dt>
<dd>Methods with these flags must be of type <code class="xref c c-type docutils literal notranslate">PyCFunctionWithKeywords</code>.
The function expects three parameters: self, args, and a dictionary of
all the keyword arguments. The flag is typically combined with
<a class="reference internal" href="#METH_VARARGS" title="METH_VARARGS"><code class="xref py py-const docutils literal notranslate">METH_VARARGS</code></a>, and the parameters are typically processed using
<a class="reference internal" href="arg.html#c.PyArg_ParseTupleAndKeywords" title="PyArg_ParseTupleAndKeywords"><code class="xref c c-func docutils literal notranslate">PyArg_ParseTupleAndKeywords()</code></a>.
</dd></dl>

<dl class="py data">
<dt class="sig sig-object py" id="METH_NOARGS">
METH_NOARGS<a class="headerlink" href="#METH_NOARGS" title="Permalink to this definition">¶</a></dt>
<dd>Methods without parameters don’t need to check whether arguments are given if
they are listed with the <a class="reference internal" href="#METH_NOARGS" title="METH_NOARGS"><code class="xref py py-const docutils literal notranslate">METH_NOARGS</code></a> flag. They need to be of type
<a class="reference internal" href="#c.PyCFunction" title="PyCFunction"><code class="xref c c-type docutils literal notranslate">PyCFunction</code></a>. The first parameter is typically named <code class="docutils literal notranslate">self</code> and
will hold a reference to the module or object instance. In all cases the
second parameter will be NULL.
</dd></dl>

<dl class="py data">
<dt class="sig sig-object py" id="METH_O">
METH_O<a class="headerlink" href="#METH_O" title="Permalink to this definition">¶</a></dt>
<dd>Methods with a single object argument can be listed with the <a class="reference internal" href="#METH_O" title="METH_O"><code class="xref py py-const docutils literal notranslate">METH_O</code></a>
flag, instead of invoking <a class="reference internal" href="arg.html#c.PyArg_ParseTuple" title="PyArg_ParseTuple"><code class="xref c c-func docutils literal notranslate">PyArg_ParseTuple()</code></a> with a <code class="docutils literal notranslate">&quot;O&quot;</code> argument.
They have the type <a class="reference internal" href="#c.PyCFunction" title="PyCFunction"><code class="xref c c-type docutils literal notranslate">PyCFunction</code></a>, with the self parameter, and a
<code class="xref c c-type docutils literal notranslate">PyObject*</code> parameter representing the single argument.
</dd></dl>

<dl class="py data">
<dt class="sig sig-object py" id="METH_OLDARGS">
METH_OLDARGS<a class="headerlink" href="#METH_OLDARGS" title="Permalink to this definition">¶</a></dt>
<dd>This calling convention is deprecated. The method must be of type
<a class="reference internal" href="#c.PyCFunction" title="PyCFunction"><code class="xref c c-type docutils literal notranslate">PyCFunction</code></a>. The second argument is NULL if no arguments are
given, a single object if exactly one argument is given, and a tuple of
objects if more than one argument is given. There is no way for a function
using this convention to distinguish between a call with multiple arguments
and a call with a tuple as the only argument.
</dd></dl>

These two constants are not used to indicate the calling convention but the
binding when use with methods of classes. These may not be used for functions
defined for modules. At most one of these flags may be set for any given
method.
<dl class="py data">
<dt class="sig sig-object py" id="METH_CLASS">
METH_CLASS<a class="headerlink" href="#METH_CLASS" title="Permalink to this definition">¶</a></dt>
<dd>The method will be passed the type object as the first parameter rather
than an instance of the type. This is used to create class methods,
similar to what is created when using the <a class="reference internal" href="../library/functions.html#classmethod" title="classmethod"><code class="xref py py-func docutils literal notranslate">classmethod()</code></a> built-in
function.
<div class="versionadded">
New in version 2.3.
</div>
</dd></dl>

<dl class="py data">
<dt class="sig sig-object py" id="METH_STATIC">
METH_STATIC<a class="headerlink" href="#METH_STATIC" title="Permalink to this definition">¶</a></dt>
<dd>The method will be passed NULL as the first parameter rather than an
instance of the type. This is used to create static methods, similar to
what is created when using the <a class="reference internal" href="../library/functions.html#staticmethod" title="staticmethod"><code class="xref py py-func docutils literal notranslate">staticmethod()</code></a> built-in function.
<div class="versionadded">
New in version 2.3.
</div>
</dd></dl>

One other constant controls whether a method is loaded in place of another
definition with the same method name.
<dl class="py data">
<dt class="sig sig-object py" id="METH_COEXIST">
METH_COEXIST<a class="headerlink" href="#METH_COEXIST" title="Permalink to this definition">¶</a></dt>
<dd>The method will be loaded in place of existing definitions. Without
METH_COEXIST, the default is to skip repeated definitions. Since slot
wrappers are loaded before the method table, the existence of a
sq_contains slot, for example, would generate a wrapped method named
<code class="xref py py-meth docutils literal notranslate">__contains__()</code> and preclude the loading of a corresponding
PyCFunction with the same name. With the flag defined, the PyCFunction
will be loaded in place of the wrapper object and will co-exist with the
slot. This is helpful because calls to PyCFunctions are optimized more
than wrapper object calls.
<div class="versionadded">
New in version 2.4.
</div>
</dd></dl>

<dl class="c type">
<dt class="sig sig-object c" id="c.PyMemberDef">
type PyMemberDef<a class="headerlink" href="#c.PyMemberDef" title="Permalink to this definition">¶</a> </dt>
<dd>Structure which describes an attribute of a type which corresponds to a C
struct member. Its fields are:
<table class="docutils align-default">
<colgroup>
<col style="width: 29%" />
<col style="width: 21%" />
<col style="width: 50%" />
</colgroup>
<thead>
<tr class="row-odd"><th class="head">Field</th>
<th class="head">C Type</th>
<th class="head">Meaning</th>
</tr>
</thead>
<tbody>
<tr class="row-even"><td><code class="xref py py-attr docutils literal notranslate">name</code></td>
<td>char *</td>
<td>name of the member</td>
</tr>
<tr class="row-odd"><td><code class="xref py py-attr docutils literal notranslate">type</code></td>
<td>int</td>
<td>the type of the member in the
C struct</td>
</tr>
<tr class="row-even"><td><code class="xref py py-attr docutils literal notranslate">offset</code></td>
<td>Py_ssize_t</td>
<td>the offset in bytes that the
member is located on the
type’s object struct</td>
</tr>
<tr class="row-odd"><td><code class="xref py py-attr docutils literal notranslate">flags</code></td>
<td>int</td>
<td>flag bits indicating if the
field should be read-only or
writable</td>
</tr>
<tr class="row-even"><td><code class="xref py py-attr docutils literal notranslate">doc</code></td>
<td>char *</td>
<td>points to the contents of the
docstring</td>
</tr>
</tbody>
</table>
<code class="xref py py-attr docutils literal notranslate">type</code> can be one of many <code class="docutils literal notranslate">T_</code> macros corresponding to various C
types. When the member is accessed in Python, it will be converted to the
equivalent Python type.
<table class="docutils align-default">
<colgroup>
<col style="width: 45%" />
<col style="width: 55%" />
</colgroup>
<thead>
<tr class="row-odd"><th class="head">Macro name</th>
<th class="head">C type</th>
</tr>
</thead>
<tbody>
<tr class="row-even"><td>T_SHORT</td>
<td>short</td>
</tr>
<tr class="row-odd"><td>T_INT</td>
<td>int</td>
</tr>
<tr class="row-even"><td>T_LONG</td>
<td>long</td>
</tr>
<tr class="row-odd"><td>T_FLOAT</td>
<td>float</td>
</tr>
<tr class="row-even"><td>T_DOUBLE</td>
<td>double</td>
</tr>
<tr class="row-odd"><td>T_STRING</td>
<td>char *</td>
</tr>
<tr class="row-even"><td>T_OBJECT</td>
<td>PyObject *</td>
</tr>
<tr class="row-odd"><td>T_OBJECT_EX</td>
<td>PyObject *</td>
</tr>
<tr class="row-even"><td>T_CHAR</td>
<td>char</td>
</tr>
<tr class="row-odd"><td>T_BYTE</td>
<td>char</td>
</tr>
<tr class="row-even"><td>T_UBYTE</td>
<td>unsigned char</td>
</tr>
<tr class="row-odd"><td>T_UINT</td>
<td>unsigned int</td>
</tr>
<tr class="row-even"><td>T_USHORT</td>
<td>unsigned short</td>
</tr>
<tr class="row-odd"><td>T_ULONG</td>
<td>unsigned long</td>
</tr>
<tr class="row-even"><td>T_BOOL</td>
<td>char</td>
</tr>
<tr class="row-odd"><td>T_LONGLONG</td>
<td>long long</td>
</tr>
<tr class="row-even"><td>T_ULONGLONG</td>
<td>unsigned long long</td>
</tr>
<tr class="row-odd"><td>T_PYSSIZET</td>
<td>Py_ssize_t</td>
</tr>
</tbody>
</table>
<code class="xref c c-macro docutils literal notranslate">T_OBJECT</code> and <code class="xref c c-macro docutils literal notranslate">T_OBJECT_EX</code> differ in that
<code class="xref c c-macro docutils literal notranslate">T_OBJECT</code> returns <code class="docutils literal notranslate">None</code> if the member is NULL and
<code class="xref c c-macro docutils literal notranslate">T_OBJECT_EX</code> raises an <code class="xref py py-exc docutils literal notranslate">AttributeError</code>. Try to use
<code class="xref c c-macro docutils literal notranslate">T_OBJECT_EX</code> over <code class="xref c c-macro docutils literal notranslate">T_OBJECT</code> because <code class="xref c c-macro docutils literal notranslate">T_OBJECT_EX</code>
handles use of the <a class="reference internal" href="../reference/simple_stmts.html#del"><code class="xref std std-keyword docutils literal notranslate">del</code></a> statement on that attribute more correctly
than <code class="xref c c-macro docutils literal notranslate">T_OBJECT</code>.
<code class="xref py py-attr docutils literal notranslate">flags</code> can be <code class="docutils literal notranslate">0</code> for write and read access or <code class="xref c c-macro docutils literal notranslate">READONLY</code> for
read-only access. Using <code class="xref c c-macro docutils literal notranslate">T_STRING</code> for <a class="reference internal" href="../library/functions.html#type" title="type"><code class="xref py py-attr docutils literal notranslate">type</code></a> implies
<code class="xref c c-macro docutils literal notranslate">READONLY</code>. Only <code class="xref c c-macro docutils literal notranslate">T_OBJECT</code> and <code class="xref c c-macro docutils literal notranslate">T_OBJECT_EX</code>
members can be deleted. (They are set to NULL).
</dd></dl>

<dl class="c type">
<dt class="sig sig-object c" id="c.PyGetSetDef">
type PyGetSetDef<a class="headerlink" href="#c.PyGetSetDef" title="Permalink to this definition">¶</a> </dt>
<dd>Structure to define property-like access for a type. See also description of
the <a class="reference internal" href="typeobj.html#c.PyTypeObject.tp_getset" title="PyTypeObject.tp_getset"><code class="xref c c-member docutils literal notranslate">PyTypeObject.tp_getset</code></a> slot.
<table class="docutils align-default">
<colgroup>
<col style="width: 20%" />
<col style="width: 27%" />
<col style="width: 53%" />
</colgroup>
<thead>
<tr class="row-odd"><th class="head">Field</th>
<th class="head">C Type</th>
<th class="head">Meaning</th>
</tr>
</thead>
<tbody>
<tr class="row-even"><td>name</td>
<td>char *</td>
<td>attribute name</td>
</tr>
<tr class="row-odd"><td>get</td>
<td>getter</td>
<td>C Function to get the attribute</td>
</tr>
<tr class="row-even"><td>set</td>
<td>setter</td>
<td>optional C function to set or
delete the attribute, if omitted
the attribute is readonly</td>
</tr>
<tr class="row-odd"><td>doc</td>
<td>char *</td>
<td>optional docstring</td>
</tr>
<tr class="row-even"><td>closure</td>
<td>void *</td>
<td>optional function pointer,
providing additional data for
getter and setter</td>
</tr>
</tbody>
</table>
The <code class="docutils literal notranslate">get</code> function takes one <code class="xref c c-type docutils literal notranslate">PyObject*</code> parameter (the
instance) and a function pointer (the associated <code class="docutils literal notranslate">closure</code>):
<div class="highlight-default notranslate"><div class="highlight"><pre>typedef PyObject *(*getter)(PyObject *, void *);
</pre></div>
</div>
It should return a new reference on success or NULL with a set exception
on failure.
<code class="docutils literal notranslate">set</code> functions take two <code class="xref c c-type docutils literal notranslate">PyObject*</code> parameters (the instance and
the value to be set) and a function pointer (the associated <code class="docutils literal notranslate">closure</code>):
<div class="highlight-default notranslate"><div class="highlight"><pre>typedef int (*setter)(PyObject *, PyObject *, void *);
</pre></div>
</div>
In case the attribute should be deleted the second parameter is NULL.
Should return <code class="docutils literal notranslate">0</code> on success or <code class="docutils literal notranslate">-1</code> with a set exception on failure.
</dd></dl>

<dl class="c function">
<dt class="sig sig-object c" id="c.Py_FindMethod">
<a class="reference internal" href="#c.PyObject" title="PyObject">PyObject</a> *Py_FindMethod(<a class="reference internal" href="#c.PyMethodDef" title="PyMethodDef">PyMethodDef</a> table[], <a class="reference internal" href="#c.PyObject" title="PyObject">PyObject</a> *ob, char *name)<a class="headerlink" href="#c.Py_FindMethod" title="Permalink to this definition">¶</a> </dt>
<dd>Return a bound method object for an extension type implemented in C. This
can be useful in the implementation of a <a class="reference internal" href="typeobj.html#c.PyTypeObject.tp_getattro" title="PyTypeObject.tp_getattro"><code class="xref c c-member docutils literal notranslate">tp_getattro</code></a> or
<a class="reference internal" href="typeobj.html#c.PyTypeObject.tp_getattr" title="PyTypeObject.tp_getattr"><code class="xref c c-member docutils literal notranslate">tp_getattr</code></a> handler that does not use the
<a class="reference internal" href="object.html#c.PyObject_GenericGetAttr" title="PyObject_GenericGetAttr"><code class="xref c c-func docutils literal notranslate">PyObject_GenericGetAttr()</code></a> function.
</dd></dl>

</section>

<div class="clearer"></div>
 </div>
 </div>
 </div>
 <div class="sphinxsidebar" role="navigation" aria-label="main navigation">
 <div class="sphinxsidebarwrapper">
 <h4>Previous topic</h4>
 <a href="allocation.html"
 title="previous chapter">Allocating Objects on the Heap</a>
 <h4>Next topic</h4>
 <a href="typeobj.html"
 title="next chapter">Type Objects</a>
 <div role="note" aria-label="source link">
 <h3>This Page</h3>
 <ul class="this-page-menu">
 <li><a href="../_sources/c-api/structures.rst.txt"
 rel="nofollow">Show Source</a></li>
 </ul>
 </div>
<div id="searchbox" style="display: none" role="search">
 <h3 id="searchlabel">Quick search</h3>
 <div class="searchformwrapper">
 <form class="search" action="../search.html" method="get">
 <input type="text" name="q" aria-labelledby="searchlabel" autocomplete="off" autocorrect="off" autocapitalize="off" spellcheck="false"/>
 <input type="submit" value="Go" />
 </form>
 </div>
</div>
<script>$('#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="typeobj.html" title="Type Objects"
 >next</a> |</li>
 <li class="right" >
 <a href="allocation.html" title="Allocating Objects on the Heap"
 >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> &#187;</li>
 <li>
 <a href="../index.html">Python 2.7.18 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="objimpl.html" >Object Implementation Support</a> &#187;</li>
 <li class="nav-item nav-item-this"><a href="">Common Object Structures</a></li> 
 </ul>
 </div> 
 <div class="footer">
 &copy; <a href="../copyright.html">Copyright</a> 1990-2024, Python Software Foundation.
 
 The Python Software Foundation is a non-profit corporation.
 <a href="https://www.python.org/psf/donations/">Please donate.</a>
 
 Last updated on November 21, 2024.
 <a href="../bugs.html">Found a bug</a>?
 
 Created using <a href="http://sphinx.pocoo.org/">Sphinx</a> 4.3.2.
 </div>

</body>
</html>