Python使用metaclass實現Singleton模式的方法

 　　本文實例講述了Python使用metaclass實現Singleton模式的方法。分享給大家供大家參考。具體實現方法如下：

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 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()

　　輸出：

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1 2 3 4 5 6 7 8 Singleton new Singleton init Singleton call Cache new Cache init <__main__.Cache object at 0x01CDB130> Singleton call <__main__.Cache object at 0x01CDB130>

　　希望本文所述對大家的Python程序設計有所幫助。