symbian-qemu-0.9.1-12/python-2.6.1/Doc/c-api/weakref.rst
author johnathan.white@2718R8BGH51.accenture.com
Mon, 08 Mar 2010 18:45:03 +0000
changeset 46 b6935a90ca64
parent 1 2fb8b9db1c86
permissions -rw-r--r--
Modify framebuffer and NGA framebuffer to read screen size from board model dtb file. Optimise memory usuage of frame buffer Add example minigui application with hooks to profiler (which writes results to S:\). Modified NGA framebuffer to run its own dfc queue at high priority

.. 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.

   .. versionadded:: 2.2


.. cfunction:: int PyWeakref_CheckRef(ob)

   Return true if *ob* is a reference object.

   .. versionadded:: 2.2


.. cfunction:: int PyWeakref_CheckProxy(ob)

   Return true if *ob* is a proxy object.

   .. versionadded:: 2.2


.. 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`.

   .. versionadded:: 2.2


.. 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`.

   .. versionadded:: 2.2


.. cfunction:: PyObject* PyWeakref_GetObject(PyObject *ref)

   Return the referenced object from a weak reference, *ref*.  If the referent is
   no longer live, returns ``None``.

   .. versionadded:: 2.2


.. cfunction:: PyObject* PyWeakref_GET_OBJECT(PyObject *ref)

   Similar to :cfunc:`PyWeakref_GetObject`, but implemented as a macro that does no
   error checking.

   .. versionadded:: 2.2