Date:2012-12-09
从形式上看,new style class继承自object或者其他新式类。old style class则不是
看他们的实例的type:
In [5]: class A:pass ...: In [6]: class B(object):pass ...: In [7]: type(A()) Out[7]: <type 'instance'> In [8]: type(B()) Out[8]: <class '__main__.B'>
old style class的实例全是<type 'instance'>
,而在new style class中,type(B)即B().__class__
注:type继承自object,是一个新式类
In [9]: type.__base__ Out[9]: <type 'object'>
其实type是object的子类,也是object的实例.object是type的父类,也是type的实例
In [13]: isinstance(type,object) Out[13]: True In [14]: isinstance(object,type) Out[14]: True