示例：

对于论坛中的帖子，需要根据帖子的点赞数，浏览数和评论数进行排序。三个排序标准的优先级顺序为：点赞数>浏览数>评论数。

也就是说，先按点赞数排序，如果点赞数相等，其次才按浏览数，最后才是评论数。

实现：

class Post:

""""""

def __init__(self,postname='',zan_num=0,view_num=0,reply_num=0):

self.postname = postname

self.zan_num = zan_num

self.view_num - view_num

self.reply_num = reply_num

def __cmp__(self,other):

if self.__eq__(other):

return 0

elif self.__lt__(other):

return -1

elif self.__gt__(other):

return 1

def __eq__(self,other):

if not isinstance(other,Post):

raise TypeError,"can't cmp other type to Post!"

if self.zan_num == other.zan_num and self.view_num == other.view_num and self.reply_num == reply_num:

return True

else:

return False

def __lt__(self,other):

if not isinstance(other,Post):

raise TypeError,"can't cmp other type to Post!"

if self.zan_num < other.zan_num:

return True

elif self.zan_num == other.zan_num and self.view_num < other.view_num:

return True

elif self.zan_num == other.zan_num and self.view_num = other.view_num and self.reply_num < other.reply_num:

return True

else:

return False

def __gt__(self,other):

if not isinstance(other,Post):

raise TypeError,"can't cmp other type to Post!"

if self.zan_num > other.zan_num:

return True

elif self.zan_num == other.zan_num and self.view_num > other.view_num:

return True

elif self.zan_num == other.zan_num and self.view_num = other.view_num and self.reply_num > other.reply_num:

return True

else:

return False

#比较

post1 = Post('abc',42,12,33)

post2 = Post('acc',52,65,34)

post3 = Post('adc',42,13,53)

post4 = Post('aec',33,12,22)

print 'post2>post1':post1>post2

#排序：

post_lst = [post1,post2,post3,post4]

post_lst.sort(key=lambda obj:obj, reverse=True)