Слабкі довідкові об’єкти¶
Python підтримує слабкі посилання як об’єкти першого класу. Існує два типи об’єктів, які безпосередньо реалізують слабкі посилання. Перший є простим довідковим об’єктом, а другий діє як проксі для оригінального об’єкта, наскільки це можливо.
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int
PyWeakref_Check
(ob)¶ Return true if ob is either a reference or proxy object. This function always succeeds.
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int
PyWeakref_CheckRef
(ob)¶ Return true if ob is a reference object. This function always succeeds.
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int
PyWeakref_CheckProxy
(ob)¶ Return true if ob is a proxy object. This function always succeeds.
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PyObject *
PyWeakref_NewRef
(PyObject *ob, PyObject *callback)¶ - Return value: New reference. Part of the Stable ABI.
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
orNULL
. If ob is not a weakly referencable object, or if callback is not callable,None
, orNULL
, this will returnNULL
and raiseTypeError
.
-
PyObject *
PyWeakref_NewProxy
(PyObject *ob, PyObject *callback)¶ - Return value: New reference. Part of the Stable ABI.
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
orNULL
. If ob is not a weakly referencable object, or if callback is not callable,None
, orNULL
, this will returnNULL
and raiseTypeError
.
-
PyObject *
PyWeakref_GetObject
(PyObject *ref)¶ - Return value: Borrowed reference. Part of the Stable ABI.
Return the referenced object from a weak reference, ref. If the referent is no longer live, returns
Py_None
.Примітка
Ця функція повертає borrowed reference на об’єкт, на який посилається. Це означає, що ви завжди повинні викликати
Py_INCREF()
для об’єкта, за винятком випадків, коли його не можна знищити перед останнім використанням запозиченого посилання.
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PyObject *
PyWeakref_GET_OBJECT
(PyObject *ref)¶ - Return value: Borrowed reference.
Similar to
PyWeakref_GetObject()
, but implemented as a macro that does no error checking.
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void
PyObject_ClearWeakRefs
(PyObject *object)¶ - Part of the Stable ABI.
This function is called by the
tp_dealloc
handler to clear weak references.This iterates through the weak references for object and calls callbacks for those references which have one. It returns when all callbacks have been attempted.