test_weakref.py 文件源码

def check_gc_during_creation(self, makeref):
        thresholds = gc.get_threshold()
        gc.set_threshold(1, 1, 1)
        gc.collect()
        class A:
            pass

        def callback(*args):
            pass

        referenced = A()

        a = A()
        a.a = a
        a.wr = makeref(referenced)

        try:
            # now make sure the object and the ref get labeled as
            # cyclic trash:
            a = A()
            weakref.ref(referenced, callback)

        finally:
            gc.set_threshold(*thresholds)