介绍：
python支持多继承，但能否支持动态继承性质呢？
在程序运行过程中，重定义类的继承，python是支持这种动态继承性质的。这便是python中 的mixin，在定义类过程中改变类的继承顺序，继承类。
当某个模块不能修改时，通过mixin方式可以动态添加该类的方法，动态改变类的原有继承体系。 弄懂了多继承，mixin特性就简单多了。
请注意mixin后的具体继承体系的改变。
#!/usr/bin/env python
import types
def MixIn(pyClass,mixInClass,makeAncestor=0):
if makeAncestor:
pyClass.__bases__ = (mixInClass,) + pyClass.__bases__
elif mixInClass not in pyClass.__bases__:
pyClass.__bases__ = pyClass.__bases__ + (mixInClass,)
else:
pass
class C1(object):
def test(self):
print 'test in C1'
class C0MixIn(object):
def test(self):
print 'test in C0MixIn'
class C2(C1,C0MixIn):
def test(self):
print 'test in C2'
class C0(C1):
pass
if __name__ == "__main__":
print C0.__mro__
c1 = C0()
c1.test()
MixIn(C0,C0MixIn,1)
c0 = C0()
c0.test()
print C0.__mro__
print C2.__mro__
MixIn(C2,C0MixIn)
print C2.__mro__
运行结果如下: python mixin2.py
(<class '__main__.C0'>, <class '__main__.C1'>, <type 'object'>)
test in C1
test in C0MixIn
(<class '__main__.C0'>, <class '__main__.C0MixIn'>, <class '__main__.C1'>, <type 'object'>)
(<class '__main__.C2'>, <class '__main__.C1'>, <class '__main__.C0MixIn'>, <type 'object'>)
(<class '__main__.C2'>, <class '__main__.C1'>, <class '__main__.C0MixIn'>, <type 'object'>)
参考资料
很详细的MixIn介绍:http://www.linuxjournal.com/node/4540/print