Refer to
Providing a C API for an Extension Module
for more information on using these objects.
Added in version 3.1.
typePyCapsule
This subtype of
represents an opaque value, useful for C extension modules which need to pass an opaque value (as a 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.
PyCapsule_Type
Part of the
.The type object corresponding to capsule objects. This is the same object as
in the Python layer.
typePyCapsule_Destructor
Part of the
.The type of a destructor callback for a capsule. Defined as:
typedefvoid(*PyCapsule_Destructor)(PyObject*);See
for the semantics of PyCapsule_Destructor callbacks.
intPyCapsule_CheckExact(
*p)
Thread safety:
.Return true if its argument is a
. This function always succeeds.
*PyCapsule_New(void*pointer, constchar*name,
destructor)
Return value: New reference. Part of the
. Thread safety:
.Create a
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
.
void*PyCapsule_GetPointer(
*capsule, constchar*name)
Part of the
. Thread safety:
Safe to call without external synchronization on distinct objects
.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 strcmp() to compare capsule names.
PyCapsule_GetDestructor(
*capsule)
Part of the
. Thread safety:
Safe to call without external synchronization on distinct objects
.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
or
to disambiguate.
void*PyCapsule_GetContext(
*capsule)
Part of the
. Thread safety:
Safe to call without external synchronization on distinct objects
.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
or
to disambiguate.
constchar*PyCapsule_GetName(
*capsule)
Part of the
. Thread safety:
Safe to call without external synchronization on distinct objects
.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
or
to disambiguate.
void*PyCapsule_Import(constchar*name, intno_block)
Part of the
. Thread safety:
Safe to call from multiple threads with external synchronization only
.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.
This function splits name on the . character, and imports the first element. It then processes further elements using attribute lookups.
Return the capsule’s internal pointer on success. On failure, set an exception and return NULL.
Note
If name points to an attribute of some submodule or subpackage, this submodule or subpackage must be previously imported using other means (for example, by using
) for the attribute lookups to succeed.
Changed in version 3.3: no_block has no effect anymore.
intPyCapsule_IsValid(
*capsule, constchar*name)
Part of the
. Thread safety:
Safe to call without external synchronization on distinct objects
.Determines whether or not capsule is a valid capsule. A valid capsule is non-NULL, passes
, has a non-NULL pointer stored in it, and its internal name matches the name parameter. (See
for information on how capsule names are compared.)
In other words, if
returns a true value, calls to any of the accessors (any function starting with 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.
intPyCapsule_SetContext(
*capsule, void*context)
Part of the
. Thread safety:
Safe to call without external synchronization on distinct objects
.Set the context pointer inside capsule to context.
Return 0 on success. Return nonzero and set an exception on failure.
intPyCapsule_SetDestructor(
*capsule,
destructor)
Part of the
. Thread safety:
Safe to call without external synchronization on distinct objects
.Set the destructor inside capsule to destructor.
Return 0 on success. Return nonzero and set an exception on failure.
intPyCapsule_SetName(
*capsule, constchar*name)
Part of the
. Thread safety:
Safe to call without external synchronization on distinct objects
.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.
intPyCapsule_SetPointer(
*capsule, void*pointer)
Part of the
. Thread safety:
Safe to call without external synchronization on distinct objects
.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.