元类例子

class AAA(type):
    def __init__(self,name,father,data):
        print('haha')
        super(AAA, self).__init__(name,father,data)

    def __call__(self, *args, **kwargs):
        print('------==')
        cc = object.__new__(self)
        self.__init__(cc, *args, **kwargs)
        print('++')
        return cc



class MySQL(object,metaclass=AAA):
    def __init__(self,host,port):
        self.host=host
        self.port=port
        print('fdsf')

    # @classmethod
    # def from_conf(cls):
    #     print(cls)
    #     return cls(settings.HOST,settings.PORT)

    def __call__(self, *args, **kwargs):
        print('-aaa-----==')

    print('aaaa')

MySQL('111',33)