In [1]: class old():   ...:     a = 1   ...:     In [2]: o = old()In [3]: o.__class__Out[3]: 
    
     In [4]: type(o)                                                                    Out[4]: instanceIn [5]: class new(object):                                                            ...:     a = 2   ...:     In [6]: n = new()In [7]: n.__class__Out[7]: __main__.newIn [8]: type(n)Out[8]: __main__.new
    

1）在多继承中，新式类采用广度优先搜索，而旧式类是采用深度优先搜索。

2）新式类更符合OOP编程思想，统一了python中的类型机制。