test_weakref.py 文件源码

def test_trashcan_16602(self):
        # Issue #16602: when a weakref's target was part of a long
        # deallocation chain, the trashcan mechanism could delay clearing
        # of the weakref and make the target object visible from outside
        # code even though its refcount had dropped to 0.  A crash ensued.
        class C(object):
            def __init__(self, parent):
                if not parent:
                    return
                wself = weakref.ref(self)
                def cb(wparent):
                    o = wself()
                self.wparent = weakref.ref(parent, cb)

        d = weakref.WeakKeyDictionary()
        root = c = C(None)
        for n in range(100):
            d[c] = c = C(c)
        del root
        gc.collect()