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It is often used to make a C function pointer defined in one module available to other modules, so the regular import mechanism can be used to access C APIs defined in dynamically loaded modules.</p> </dd></dl> <dl class="c type"> <dt class="sig sig-object c" id="c.PyCapsule_Destructor"> <span class="k"><span class="pre">type</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">PyCapsule_Destructor</span></span></span><a class="headerlink" href="#c.PyCapsule_Destructor" title="Link 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>The type of a destructor callback for a capsule. Defined as:</p> <div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="k">typedef</span><span class="w"> </span><span class="kt">void</span><span class="w"> </span><span class="p">(</span><span class="o">*</span><span class="n">PyCapsule_Destructor</span><span class="p">)(</span><span class="n">PyObject</span><span class="w"> </span><span class="o">*</span><span class="p">);</span> </pre></div> </div> <p>See <a class="reference internal" href="#c.PyCapsule_New" title="PyCapsule_New"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyCapsule_New()</span></code></a> for the semantics of PyCapsule_Destructor callbacks.</p> </dd></dl> <dl class="c function"> <dt class="sig sig-object c" id="c.PyCapsule_CheckExact"> <span class="kt"><span class="pre">int</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">PyCapsule_CheckExact</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">p</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.PyCapsule_CheckExact" title="Link to this definition">¶</a><br /></dt> <dd><p>Return true if its argument is a <a class="reference internal" href="#c.PyCapsule" title="PyCapsule"><code class="xref c c-type docutils literal notranslate"><span class="pre">PyCapsule</span></code></a>. This function always succeeds.</p> </dd></dl> <dl class="c function"> <dt class="sig sig-object c" id="c.PyCapsule_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">PyCapsule_New</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">pointer</span></span>, <span class="k"><span class="pre">const</span></span><span class="w"> </span><span class="kt"><span class="pre">char</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">name</span></span>, <a class="reference internal" href="#c.PyCapsule_Destructor" title="PyCapsule_Destructor"><span class="n"><span class="pre">PyCapsule_Destructor</span></span></a><span class="w"> </span><span class="n"><span class="pre">destructor</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.PyCapsule_New" title="Link to this definition">¶</a><br /></dt> <dd><em class="refcount return_new_ref">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>Create a <a class="reference internal" href="#c.PyCapsule" title="PyCapsule"><code class="xref c c-type docutils literal notranslate"><span class="pre">PyCapsule</span></code></a> encapsulating the <em>pointer</em>. The <em>pointer</em> argument may not be <code class="docutils literal notranslate"><span class="pre">NULL</span></code>.</p> <p>On failure, set an exception and return <code class="docutils literal notranslate"><span class="pre">NULL</span></code>.</p> <p>The <em>name</em> string may either be <code class="docutils literal notranslate"><span class="pre">NULL</span></code> or a pointer to a valid C string. If non-<code class="docutils literal notranslate"><span class="pre">NULL</span></code>, this string must outlive the capsule. (Though it is permitted to free it inside the <em>destructor</em>.)</p> <p>If the <em>destructor</em> argument is not <code class="docutils literal notranslate"><span class="pre">NULL</span></code>, it will be called with the capsule as its argument when it is destroyed.</p> <p>If this capsule will be stored as an attribute of a module, the <em>name</em> should be specified as <code class="docutils literal notranslate"><span class="pre">modulename.attributename</span></code>. This will enable other modules to import the capsule using <a class="reference internal" href="#c.PyCapsule_Import" title="PyCapsule_Import"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyCapsule_Import()</span></code></a>.</p> </dd></dl> <dl class="c function"> <dt class="sig sig-object c" id="c.PyCapsule_GetPointer"> <span class="kt"><span class="pre">void</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="sig-name descname"><span class="n"><span class="pre">PyCapsule_GetPointer</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">capsule</span></span>, <span class="k"><span class="pre">const</span></span><span class="w"> </span><span class="kt"><span class="pre">char</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">name</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.PyCapsule_GetPointer" title="Link 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>Retrieve the <em>pointer</em> stored in the capsule. On failure, set an exception and return <code class="docutils literal notranslate"><span class="pre">NULL</span></code>.</p> <p>The <em>name</em> parameter must compare exactly to the name stored in the capsule. If the name stored in the capsule is <code class="docutils literal notranslate"><span class="pre">NULL</span></code>, the <em>name</em> passed in must also be <code class="docutils literal notranslate"><span class="pre">NULL</span></code>. Python uses the C function <code class="xref c c-func docutils literal notranslate"><span class="pre">strcmp()</span></code> to compare capsule names.</p> </dd></dl> <dl class="c function"> <dt class="sig sig-object c" id="c.PyCapsule_GetDestructor"> <a class="reference internal" href="#c.PyCapsule_Destructor" title="PyCapsule_Destructor"><span class="n"><span class="pre">PyCapsule_Destructor</span></span></a><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">PyCapsule_GetDestructor</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">capsule</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.PyCapsule_GetDestructor" title="Link 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>Return the current destructor stored in the capsule. On failure, set an exception and return <code class="docutils literal notranslate"><span class="pre">NULL</span></code>.</p> <p>It is legal for a capsule to have a <code class="docutils literal notranslate"><span class="pre">NULL</span></code> destructor. This makes a <code class="docutils literal notranslate"><span class="pre">NULL</span></code> return code somewhat ambiguous; use <a class="reference internal" href="#c.PyCapsule_IsValid" title="PyCapsule_IsValid"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyCapsule_IsValid()</span></code></a> or <a class="reference internal" href="exceptions.html#c.PyErr_Occurred" title="PyErr_Occurred"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyErr_Occurred()</span></code></a> to disambiguate.</p> </dd></dl> <dl class="c function"> <dt class="sig sig-object c" id="c.PyCapsule_GetContext"> <span class="kt"><span class="pre">void</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="sig-name descname"><span class="n"><span class="pre">PyCapsule_GetContext</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">capsule</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.PyCapsule_GetContext" title="Link 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>Return the current context stored in the capsule. On failure, set an exception and return <code class="docutils literal notranslate"><span class="pre">NULL</span></code>.</p> <p>It is legal for a capsule to have a <code class="docutils literal notranslate"><span class="pre">NULL</span></code> context. This makes a <code class="docutils literal notranslate"><span class="pre">NULL</span></code> return code somewhat ambiguous; use <a class="reference internal" href="#c.PyCapsule_IsValid" title="PyCapsule_IsValid"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyCapsule_IsValid()</span></code></a> or <a class="reference internal" href="exceptions.html#c.PyErr_Occurred" title="PyErr_Occurred"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyErr_Occurred()</span></code></a> to disambiguate.</p> </dd></dl> <dl class="c function"> <dt class="sig sig-object c" id="c.PyCapsule_GetName"> <span class="k"><span class="pre">const</span></span><span class="w"> </span><span class="kt"><span class="pre">char</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="sig-name descname"><span class="n"><span class="pre">PyCapsule_GetName</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">capsule</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.PyCapsule_GetName" title="Link 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>Return the current name stored in the capsule. On failure, set an exception and return <code class="docutils literal notranslate"><span class="pre">NULL</span></code>.</p> <p>It is legal for a capsule to have a <code class="docutils literal notranslate"><span class="pre">NULL</span></code> name. This makes a <code class="docutils literal notranslate"><span class="pre">NULL</span></code> return code somewhat ambiguous; use <a class="reference internal" href="#c.PyCapsule_IsValid" title="PyCapsule_IsValid"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyCapsule_IsValid()</span></code></a> or <a class="reference internal" href="exceptions.html#c.PyErr_Occurred" title="PyErr_Occurred"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyErr_Occurred()</span></code></a> to disambiguate.</p> </dd></dl> <dl class="c function"> <dt class="sig sig-object c" id="c.PyCapsule_Import"> <span class="kt"><span class="pre">void</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="sig-name descname"><span class="n"><span class="pre">PyCapsule_Import</span></span></span><span class="sig-paren">(</span><span class="k"><span class="pre">const</span></span><span class="w"> </span><span class="kt"><span class="pre">char</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">name</span></span>, <span class="kt"><span class="pre">int</span></span><span class="w"> </span><span class="n"><span class="pre">no_block</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.PyCapsule_Import" title="Link 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>Import a pointer to a C object from a capsule attribute in a module. The <em>name</em> parameter should specify the full name to the attribute, as in <code class="docutils literal notranslate"><span class="pre">module.attribute</span></code>. The <em>name</em> stored in the capsule must match this string exactly.</p> <p>Return the capsule’s internal <em>pointer</em> on success. On failure, set an exception and return <code class="docutils literal notranslate"><span class="pre">NULL</span></code>.</p> <div class="versionchanged"> <p><span class="versionmodified changed">Changed in version 3.3: </span><em>no_block</em> has no effect anymore.</p> </div> </dd></dl> <dl class="c function"> <dt class="sig sig-object c" id="c.PyCapsule_IsValid"> <span class="kt"><span class="pre">int</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">PyCapsule_IsValid</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">capsule</span></span>, <span class="k"><span class="pre">const</span></span><span class="w"> </span><span class="kt"><span class="pre">char</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">name</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.PyCapsule_IsValid" title="Link 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>Determines whether or not <em>capsule</em> is a valid capsule. A valid capsule is non-<code class="docutils literal notranslate"><span class="pre">NULL</span></code>, passes <a class="reference internal" href="#c.PyCapsule_CheckExact" title="PyCapsule_CheckExact"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyCapsule_CheckExact()</span></code></a>, has a non-<code class="docutils literal notranslate"><span class="pre">NULL</span></code> pointer stored in it, and its internal name matches the <em>name</em> parameter. (See <a class="reference internal" href="#c.PyCapsule_GetPointer" title="PyCapsule_GetPointer"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyCapsule_GetPointer()</span></code></a> for information on how capsule names are compared.)</p> <p>In other words, if <a class="reference internal" href="#c.PyCapsule_IsValid" title="PyCapsule_IsValid"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyCapsule_IsValid()</span></code></a> returns a true value, calls to any of the accessors (any function starting with <code class="docutils literal notranslate"><span class="pre">PyCapsule_Get</span></code>) are guaranteed to succeed.</p> <p>Return a nonzero value if the object is valid and matches the name passed in. Return <code class="docutils literal notranslate"><span class="pre">0</span></code> otherwise. This function will not fail.</p> </dd></dl> <dl class="c function"> <dt class="sig sig-object c" id="c.PyCapsule_SetContext"> <span class="kt"><span class="pre">int</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">PyCapsule_SetContext</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">capsule</span></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">context</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.PyCapsule_SetContext" title="Link 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>Set the context pointer inside <em>capsule</em> to <em>context</em>.</p> <p>Return <code class="docutils literal notranslate"><span class="pre">0</span></code> on success. Return nonzero and set an exception on failure.</p> </dd></dl> <dl class="c function"> <dt class="sig sig-object c" id="c.PyCapsule_SetDestructor"> <span class="kt"><span class="pre">int</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">PyCapsule_SetDestructor</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">capsule</span></span>, <a class="reference internal" href="#c.PyCapsule_Destructor" title="PyCapsule_Destructor"><span class="n"><span class="pre">PyCapsule_Destructor</span></span></a><span class="w"> </span><span class="n"><span class="pre">destructor</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.PyCapsule_SetDestructor" title="Link 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>Set the destructor inside <em>capsule</em> to <em>destructor</em>.</p> <p>Return <code class="docutils literal notranslate"><span class="pre">0</span></code> on success. Return nonzero and set an exception on failure.</p> </dd></dl> <dl class="c function"> <dt class="sig sig-object c" id="c.PyCapsule_SetName"> <span class="kt"><span class="pre">int</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">PyCapsule_SetName</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">capsule</span></span>, <span class="k"><span class="pre">const</span></span><span class="w"> </span><span class="kt"><span class="pre">char</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">name</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.PyCapsule_SetName" title="Link 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>Set the name inside <em>capsule</em> to <em>name</em>. If non-<code class="docutils literal notranslate"><span class="pre">NULL</span></code>, the name must outlive the capsule. If the previous <em>name</em> stored in the capsule was not <code class="docutils literal notranslate"><span class="pre">NULL</span></code>, no attempt is made to free it.</p> <p>Return <code class="docutils literal notranslate"><span class="pre">0</span></code> on success. Return nonzero and set an exception on failure.</p> </dd></dl> <dl class="c function"> <dt class="sig sig-object c" id="c.PyCapsule_SetPointer"> <span class="kt"><span class="pre">int</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">PyCapsule_SetPointer</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">capsule</span></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">pointer</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.PyCapsule_SetPointer" title="Link 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>Set the void pointer inside <em>capsule</em> to <em>pointer</em>. The pointer may not be <code class="docutils literal notranslate"><span class="pre">NULL</span></code>.</p> <p>Return <code class="docutils literal notranslate"><span class="pre">0</span></code> on success. 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