7.5.8 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.
- int PyWeakref_Check(ob)
-
Return true if ob is either a reference or proxy object.
New in version 2.2.
- int PyWeakref_CheckRef(ob)
-
Return true if ob is a reference object.
New in version 2.2.
- int PyWeakref_CheckProxy(ob)
-
Return true if ob is a proxy object.
New in version 2.2.
- PyObject* PyWeakref_NewRef(PyObject *ob,
PyObject *callback)
-
Return value:
New reference.
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 paramter, 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 TypeError.
New in version 2.2.
- PyObject* PyWeakref_NewProxy(PyObject *ob,
PyObject *callback)
-
Return value:
New reference.
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 paramter, 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
TypeError.
New in version 2.2.
- PyObject* PyWeakref_GetObject(PyObject *ref)
-
Return value:
Borrowed reference.
Returns the referenced object from a weak reference, ref. If
the referent is no longer live, returns NULL.
New in version 2.2.
- PyObject* PyWeakref_GET_OBJECT(PyObject *ref)
-
Return value:
Borrowed reference.
Similar to PyWeakref_GetObject(), but implemented as a
macro that does no error checking.
New in version 2.2.
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