[深入Python]Alex Martelli的Borg类

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#!/usr/bin/env python #coding:utf-8   class Borg(object):     _share_state = {}     def __init__ (self):         '''         将__dict__和_share_state指向了同一个地址         这样会使_share_state的内容始终保持与__dict__同步         由于_share_state是类变量，最终就可以实现多个实例的__dict__保持同步的效果         '''         self.__dict__ = self._share_state   class Singleton(Borg):     def __init__ (self, *args, **kwargs):         super(Singleton, self).__init__()         self.val = args[0]     def __str__ (self):         return self.val   x = Singleton('test1') y = Singleton('test2') z = Singleton('test3')   print x #test3 print y #test3 print z #test3

 本文涉及的知识点：

1、__dict__

2、类变量

3、super

4、__str__

5、Python赋值的原理