本文实例讲述了Python使用metaclass实现Singleton模式的方法。分享给大家供大家参考。具体实现方法如下：
class Singleton(type): def __call__(cls, *args, **kwargs): print "Singleton call" if not hasattr(cls, 'instance'): cls.instance = super(Singleton, cls).__call__(*args, **kwargs) return cls.instance def __new__(cls, name, bases, dct): print "Singleton new" return type.__new__(cls, name, bases, dct) def __init__(cls, name, bases, dct): print "Singleton init" super(Singleton, cls).__init__(name, bases, dct) class Cache(object): __metaclass__ = Singleton def __new__(cls, *args, **kwargs): print "Cache new" return object.__new__(cls, *args, **kwargs) def __init__(cls, *args, **kwargs): print "Cache init" def __call__(cls, *args, **kwargs): print "Cache call" print Cache() print Cache()
输出：
Singleton new Singleton init Singleton call Cache new Cache init <__main__.Cache object at 0x01CDB130> Singleton call <__main__.Cache object at 0x01CDB130>
希望本文所述对大家的Python程序设计有所帮助。
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