关于python的元类的问题

最近在学习元类。

#python3
# coding=utf-8
class ModelMetaclass(type):

    def __new__(cls, name, bases, attrs):
        print("ainia")
        return type.__new__(cls, name, bases, attrs)
class BBB:
    def __new__(cls, name, bases, attrs):
        print("BBBBB")
        return object.__new__(cls, name, bases, attrs)
class Model(metaclass=BBB):
    pass
class Model2(metaclass=ModelMetaclass):
    pass
#python2
# coding=utf-8
class ModelMetaclass(type):
    def __new__(cls, name, bases, attrs):
        print("ainia")
        return type.__new__(cls, name, bases, attrs)
class BBB(object):
    def __new__(cls, name, bases, attrs):
        print("BBBBB")
        return object.__new__(cls, name, bases, attrs)
class Model(object):
    __metaclass__ = BBB
    pass
class Model2(object):
    __metaclass__ = ModelMetaclass
    pass

以上代码另存为test.py,中运行时提示:

Traceback (most recent call last):
  File "test2.py", line 18, in <module>
    class Model(metaclass=BBB):
  File "test2.py", line 15, in __new__
    return object.__new__(cls, name, bases, attrs)
TypeError: object() takes no parameters

但是如果我把return object.__new__(cls, name, bases, attrs)修改为return object.__new__(cls)却可以正常输出。
还请各位指教?

查看回复