Python 3.x中的最终课程-Guido没告诉我什么？

Python 3.x中的最终课程-Guido没告诉我什么？

您可以很容易地从Python 3.x模拟相同的效果：

class Final(type):    def __new__(cls, name, bases, classdict):        for b in bases: if isinstance(b, Final):     raise TypeError("type '{0}' is not an acceptable base type".format(b.__name__))        return type.__new__(cls, name, bases, dict(classdict))class C(metaclass=Final): passclass D(C): pass

将给出以下输出：

Traceback (most recent call last):  File "C:Tempfinal.py", line 10, in <module>    class D(C): pass  File "C:Tempfinal.py", line 5, in __new__    raise TypeError("type '{0}' is not an acceptable base type".format(b.__name__))TypeError: type 'C' is not an acceptable base type