# 약한 참조 객체

파이썬은 약한 참조를 1급 객체로 지원합니다. 약한 참조를 직접 구현하는 두 가지 구체적인 객체 형이 있습니다. 첫 번째는 간단한 참조 객체이며, 두 번째는 가능한 한 원래 객체의 프락시 역할을 합니다.

int `PyWeakref_Check`(ob)

  Return true if ob is either a reference or proxy object. This function always succeeds.

int `PyWeakref_CheckRef`(ob)

  Return true if ob is a reference object. This function always succeeds.

int `PyWeakref_CheckProxy`(ob)

  Return true if ob is a proxy object. This function always succeeds.

PyObject *`PyWeakref_NewRef`(PyObject *ob, PyObject *callback)
  반환값: 새 참조. 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` 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`.

PyObject *`PyWeakref_NewProxy`(PyObject *ob, PyObject *callback)
  반환값: 새 참조. 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` 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`.

PyObject *`PyWeakref_GetObject`(PyObject *ref)
  반환값: 빌린 참조. Part of the Stable ABI.

  Return the referenced object from a weak reference, ref. If the referent is no longer live, returns `Py_None`.

  참고

  이 함수는 참조된 객체에 대한 빌린 참조를 반환합니다. 이는 빌린 참조의 마지막 사용 전에 파괴될 수 없을 때를 제외하고, 객체에 대해 항상 `Py_INCREF()`를 호출해야 함을 뜻합니다.

PyObject *`PyWeakref_GET_OBJECT`(PyObject *ref)
  반환값: 빌린 참조.

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

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.