test_descr.py 文件源码

def test_funny_new(self):
        # Testing __new__ returning something unexpected...
        class C(object):
            def __new__(cls, arg):
                if isinstance(arg, str): return [1, 2, 3]
                elif isinstance(arg, int): return object.__new__(D)
                else: return object.__new__(cls)
        class D(C):
            def __init__(self, arg):
                self.foo = arg
        self.assertEqual(C("1"), [1, 2, 3])
        self.assertEqual(D("1"), [1, 2, 3])
        d = D(None)
        self.assertEqual(d.foo, None)
        d = C(1)
        self.assertIsInstance(d, D)
        self.assertEqual(d.foo, 1)
        d = D(1)
        self.assertIsInstance(d, D)
        self.assertEqual(d.foo, 1)