FM / c-api

/usr/share/doc/python3-docs/html/_sources/c-api/

/usr/share/doc/python3-docs/html/_sources/c-api

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abstract.rst.txt	715	0644	edit dl rm
allocation.rst.txt	2653	0644	edit dl rm
apiabiversion.rst.txt	2242	0644	edit dl rm
arg.rst.txt	30651	0644	edit dl rm
bool.rst.txt	1200	0644	edit dl rm
buffer.rst.txt	22267	0644	edit dl rm
bytearray.rst.txt	2250	0644	edit dl rm
bytes.rst.txt	9211	0644	edit dl rm
capsule.rst.txt	5741	0644	edit dl rm
cell.rst.txt	1940	0644	edit dl rm
code.rst.txt	1666	0644	edit dl rm
codec.rst.txt	4799	0644	edit dl rm
complex.rst.txt	3946	0644	edit dl rm
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conversion.rst.txt	5516	0644	edit dl rm
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datetime.rst.txt	6415	0644	edit dl rm
descriptor.rst.txt	1111	0644	edit dl rm
dict.rst.txt	7952	0644	edit dl rm
exceptions.rst.txt	47814	0644	edit dl rm
file.rst.txt	3248	0644	edit dl rm
float.rst.txt	2243	0644	edit dl rm
function.rst.txt	3348	0644	edit dl rm
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Edit: /usr/share/doc/python3-docs/html/_sources/c-api/capsule.rst.txt (5741B)

.. highlightlang:: c

.. _capsules:

Capsules
--------

.. index:: object: Capsule

Refer to :ref:`using-capsules` for more information on using these objects.

.. versionadded:: 3.1

.. c:type:: PyCapsule

This subtype of :c:type:`PyObject` represents an opaque value, useful for C
   extension modules who need to pass an opaque value (as a :c:type:`void\*`
   pointer) through Python code to other C code.  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.

.. c:type:: PyCapsule_Destructor

The type of a destructor callback for a capsule.  Defined as::

typedef void (*PyCapsule_Destructor)(PyObject *);

See :c:func:`PyCapsule_New` for the semantics of PyCapsule_Destructor
   callbacks.

.. c:function:: int PyCapsule_CheckExact(PyObject *p)

Return true if its argument is a :c:type:`PyCapsule`.

.. c:function:: PyObject* PyCapsule_New(void *pointer, const char *name, PyCapsule_Destructor destructor)

Create a :c:type:`PyCapsule` encapsulating the *pointer*.  The *pointer*
   argument may not be *NULL*.

On failure, set an exception and return *NULL*.

The *name* string may either be *NULL* or a pointer to a valid C string.  If
   non-*NULL*, this string must outlive the capsule.  (Though it is permitted to
   free it inside the *destructor*.)

If the *destructor* argument is not *NULL*, it will be called with the
   capsule as its argument when it is destroyed.

If this capsule will be stored as an attribute of a module, the *name* should
   be specified as ``modulename.attributename``.  This will enable other modules
   to import the capsule using :c:func:`PyCapsule_Import`.

.. c:function:: void* PyCapsule_GetPointer(PyObject *capsule, const char *name)

Retrieve the *pointer* stored in the capsule.  On failure, set an exception
   and return *NULL*.

The *name* parameter must compare exactly to the name stored in the capsule.
   If the name stored in the capsule is *NULL*, the *name* passed in must also
   be *NULL*.  Python uses the C function :c:func:`strcmp` to compare capsule
   names.

.. c:function:: PyCapsule_Destructor PyCapsule_GetDestructor(PyObject *capsule)

Return the current destructor stored in the capsule.  On failure, set an
   exception and return *NULL*.

It is legal for a capsule to have a *NULL* destructor.  This makes a *NULL*
   return code somewhat ambiguous; use :c:func:`PyCapsule_IsValid` or
   :c:func:`PyErr_Occurred` to disambiguate.

.. c:function:: void* PyCapsule_GetContext(PyObject *capsule)

Return the current context stored in the capsule.  On failure, set an
   exception and return *NULL*.

It is legal for a capsule to have a *NULL* context.  This makes a *NULL*
   return code somewhat ambiguous; use :c:func:`PyCapsule_IsValid` or
   :c:func:`PyErr_Occurred` to disambiguate.

.. c:function:: const char* PyCapsule_GetName(PyObject *capsule)

Return the current name stored in the capsule.  On failure, set an exception
   and return *NULL*.

It is legal for a capsule to have a *NULL* name.  This makes a *NULL* return
   code somewhat ambiguous; use :c:func:`PyCapsule_IsValid` or
   :c:func:`PyErr_Occurred` to disambiguate.

.. c:function:: void* PyCapsule_Import(const char *name, int no_block)

Import a pointer to a C object from a capsule attribute in a module.  The
   *name* parameter should specify the full name to the attribute, as in
   ``module.attribute``.  The *name* stored in the capsule must match this
   string exactly.  If *no_block* is true, import the module without blocking
   (using :c:func:`PyImport_ImportModuleNoBlock`).  If *no_block* is false,
   import the module conventionally (using :c:func:`PyImport_ImportModule`).

Return the capsule's internal *pointer* on success.  On failure, set an
   exception and return *NULL*.

.. c:function:: int PyCapsule_IsValid(PyObject *capsule, const char *name)

Determines whether or not *capsule* is a valid capsule.  A valid capsule is
   non-*NULL*, passes :c:func:`PyCapsule_CheckExact`, has a non-*NULL* pointer
   stored in it, and its internal name matches the *name* parameter.  (See
   :c:func:`PyCapsule_GetPointer` for information on how capsule names are
   compared.)

In other words, if :c:func:`PyCapsule_IsValid` returns a true value, calls to
   any of the accessors (any function starting with :c:func:`PyCapsule_Get`) are
   guaranteed to succeed.

Return a nonzero value if the object is valid and matches the name passed in.
   Return ``0`` otherwise.  This function will not fail.

.. c:function:: int PyCapsule_SetContext(PyObject *capsule, void *context)

Set the context pointer inside *capsule* to *context*.

Return ``0`` on success.  Return nonzero and set an exception on failure.

.. c:function:: int PyCapsule_SetDestructor(PyObject *capsule, PyCapsule_Destructor destructor)

Set the destructor inside *capsule* to *destructor*.

Return ``0`` on success.  Return nonzero and set an exception on failure.

.. c:function:: int PyCapsule_SetName(PyObject *capsule, const char *name)

Set the name inside *capsule* to *name*.  If non-*NULL*, the name must
   outlive the capsule.  If the previous *name* stored in the capsule was not
   *NULL*, no attempt is made to free it.

Return ``0`` on success.  Return nonzero and set an exception on failure.

.. c:function:: int PyCapsule_SetPointer(PyObject *capsule, void *pointer)

Set the void pointer inside *capsule* to *pointer*.  The pointer may not be
   *NULL*.

Return ``0`` on success.  Return nonzero and set an exception on failure.

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