弱引用对象

Python 支持 “弱引用” 作为一类对象。具体来说,有两种直接实现弱引用的对象。第一种就是简单的引用对象,第二种尽可能地作用为一个原对象的代理。

int PyWeakref_Check(PyObject *ob)

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

int PyWeakref_CheckRef(PyObject *ob)

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

int PyWeakref_CheckProxy(PyObject *ob)

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

PyObject *PyWeakref_NewRef(PyObject *ob, PyObject *callback)
返回值:新的引用。 属于 稳定 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 referenceable object, or if callback is not callable, None, or NULL, this will return NULL and raise TypeError.

PyObject *PyWeakref_NewProxy(PyObject *ob, PyObject *callback)
返回值:新的引用。 属于 稳定 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 referenceable object, or if callback is not callable, None, or NULL, this will return NULL and raise TypeError.

PyObject *PyWeakref_GetObject(PyObject *ref)
返回值:借入的引用。 属于 稳定 ABI.

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

备注

该函数返回被引用对象的一个 borrowed reference。 这意味着应该总是在该对象上调用 Py_INCREF(),除非是当它在借入引用的最后一次被使用之前无法被销毁的时候。

PyObject *PyWeakref_GET_OBJECT(PyObject *ref)
返回值:借入的引用。

类似于 PyWeakref_GetObject(),但是不带错误检测。

void PyObject_ClearWeakRefs(PyObject *object)
属于 稳定 ABI.

此函数将被 tp_dealloc 处理器调用以清空弱引用。

此函数将迭代 object 的弱引用并调用这些引用中可能存在的回调。 它将在尝试了所有回调之后返回。