test_weakref.py 文件源码

def test_order(self):
        a = self.A()
        res = []

        f1 = weakref.finalize(a, res.append, 'f1')
        f2 = weakref.finalize(a, res.append, 'f2')
        f3 = weakref.finalize(a, res.append, 'f3')
        f4 = weakref.finalize(a, res.append, 'f4')
        f5 = weakref.finalize(a, res.append, 'f5')

        # make sure finalizers can keep themselves alive
        del f1, f4

        self.assertTrue(f2.alive)
        self.assertTrue(f3.alive)
        self.assertTrue(f5.alive)

        self.assertTrue(f5.detach())
        self.assertFalse(f5.alive)

        f5()                       # nothing because previously unregistered
        res.append('A')
        f3()                       # => res.append('f3')
        self.assertFalse(f3.alive)
        res.append('B')
        f3()                       # nothing because previously called
        res.append('C')
        del a
        self._collect_if_necessary()
                                   # => res.append('f4')
                                   # => res.append('f2')
                                   # => res.append('f1')
        self.assertFalse(f2.alive)
        res.append('D')
        f2()                       # nothing because previously called by gc

        expected = ['A', 'f3', 'B', 'C', 'f4', 'f2', 'f1', 'D']
        self.assertEqual(res, expected)