circular-reference.py

class A:
    def __init__(self):
        print("A.__init__", self)
        self.other = None

    def __del__(self):
        print("A.__del__", self)


class Binder:
    def __init__(self, o1, o2):
        o1.other = o2
        o2.other = o1

    def __del__(self):
        print("Binder.__del__", self)


def f():
    a1 = A()
    a2 = A()
    Binder(a1, a2)

    print(("bound: " + 4 * "\n{}").format(a1, a1.other, a2, a2.other))


f()
print("done")