Python中的单例模式

#!/usr/bin/env python

class Singleton(type):
    _instances = {}
    def __call__(cls, *args, **kwargs):
        if cls not in cls._instances:
            cls._instances[cls] = super(Singleton, cls).__call__(*args, **kwargs)
        return cls._instances[cls]
 
    
class Logger(object):
    __metaclass__ = Singleton
    def __init__(self, id, name):
        self.id = id
        self.name = name
    def display(self):
        print self.id
        print self.name

######## test ###########
log1 = Logger(id = 1, name = '1')
log2 = Logger(id = 2, name = '2')
print log1 is log2
log1.display()
log2.display()

https://stackoverflow.com/questions/6760685/creating-a-singleton-in-python