Python继承中的元类

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继承中的元类

首先写代码测试的时候发现问题

class MetaClassTest1class(type):def __new__(cls, clsname, bases, dct):dct['test'] = 1return super(MetaClassTest1class, cls).__new__(cls, clsname, bases, dct)class MetaClassTest2class(type):def __new__(cls, clsname, bases, dct):dct['test'] = 2return super(MetaClassTest2class, cls).__new__(cls, clsname, bases, dct)class MetaClassTest3class(type):def __new__(cls, clsname, bases, dct):dct['test'] = 3return super(MetaClassTest3class, cls).__new__(cls, clsname, bases, dct)__metaclass__ = MetaClassTest1classclass Foo():__metaclass__ = MetaClassTest2classpassclass FooChild(Foo):__metaclass__ = MetaClassTest3classpassf = Foo()
print f.test

运行的结果是

TypeError                                 Traceback (most recent call last)
<ipython-input-52-81f8a2dedcb4> in <module>()24     pass25 
---> 26 class FooChild(Foo):27     __metaclass__ = MetaClassTest3class28     pass<ipython-input-52-81f8a2dedcb4> in __new__(cls, clsname, bases, dct)

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