mirror of
https://github.com/python/cpython.git
synced 2025-11-04 03:44:55 +00:00
62 lines
2.3 KiB
ReStructuredText
62 lines
2.3 KiB
ReStructuredText
.. highlightlang:: c
|
|
|
|
.. _weakrefobjects:
|
|
|
|
Weak Reference Objects
|
|
----------------------
|
|
|
|
Python supports *weak references* as first-class objects. There are two
|
|
specific object types which directly implement weak references. The first is a
|
|
simple reference object, and the second acts as a proxy for the original object
|
|
as much as it can.
|
|
|
|
|
|
.. cfunction:: int PyWeakref_Check(ob)
|
|
|
|
Return true if *ob* is either a reference or proxy object.
|
|
|
|
|
|
.. cfunction:: int PyWeakref_CheckRef(ob)
|
|
|
|
Return true if *ob* is a reference object.
|
|
|
|
|
|
.. cfunction:: int PyWeakref_CheckProxy(ob)
|
|
|
|
Return true if *ob* is a proxy object.
|
|
|
|
|
|
.. cfunction:: PyObject* PyWeakref_NewRef(PyObject *ob, PyObject *callback)
|
|
|
|
Return a weak reference object for the object *ob*. This will always return
|
|
a new reference, but is not guaranteed to create a new object; an existing
|
|
reference object may be returned. The second parameter, *callback*, can be a
|
|
callable object that receives notification when *ob* is garbage collected; it
|
|
should accept a single parameter, which will be the weak reference object
|
|
itself. *callback* may also be ``None`` or *NULL*. If *ob* is not a
|
|
weakly-referencable object, or if *callback* is not callable, ``None``, or
|
|
*NULL*, this will return *NULL* and raise :exc:`TypeError`.
|
|
|
|
|
|
.. cfunction:: PyObject* PyWeakref_NewProxy(PyObject *ob, PyObject *callback)
|
|
|
|
Return a weak reference proxy object for the object *ob*. This will always
|
|
return a new reference, but is not guaranteed to create a new object; an
|
|
existing proxy object may be returned. The second parameter, *callback*, can
|
|
be a callable object that receives notification when *ob* is garbage
|
|
collected; it should accept a single parameter, which will be the weak
|
|
reference object itself. *callback* may also be ``None`` or *NULL*. If *ob*
|
|
is not a weakly-referencable object, or if *callback* is not callable,
|
|
``None``, or *NULL*, this will return *NULL* and raise :exc:`TypeError`.
|
|
|
|
|
|
.. cfunction:: PyObject* PyWeakref_GetObject(PyObject *ref)
|
|
|
|
Return the referenced object from a weak reference, *ref*. If the referent is
|
|
no longer live, returns ``None``.
|
|
|
|
|
|
.. cfunction:: PyObject* PyWeakref_GET_OBJECT(PyObject *ref)
|
|
|
|
Similar to :cfunc:`PyWeakref_GetObject`, but implemented as a macro that does no
|
|
error checking.
|