class MyType(type):    def __init__(self, a, b, c):        print('元类构造函数执行')    def __call__(self, *args, **kwargs):        obj = object.__new__(self)        self.__init__(obj, *args, **kwargs)        return objclass Foo(metaclass=MyType):    def __init__(self, name):        self.name = nameprint(Foo)f = Foo('alex')