python单例装饰器

单例是设计结构中一种常见的模式。在工程中，确保一个实例、确保日志被初始化一次等，就可以使用单例。下面是使用python的装饰器实现的一个单例模式。可以装饰类和函数。

#!/usr/bin/env python
# -*- encoding: utf-8 -*-
"""singleton decoratorusage:decorete function: this function just be executed once.@singlentondef fun():    # do something    returndecorate class: this class just have one instance.@singletonclass MyClass(object):    def __init__():        pass"""
singleton decorator

usage:

decorete function: this function just be executed once.
@singlenton
def fun():
    # do something
    return

decorate class: this class just have one instance.
@singleton
class MyClass(object):
    def __init__():
        pass
"""
def singleton(cls):
    instances = {}
    def _singleton(*args, **kw):
        if cls not in instances:
            instances[cls] = cls(*args, **kw)
        return instances[cls]
    return _singleton