"""http://codesnipers.com/?q=python-flyweights""" import weakref class Card(object): """The object pool. Has builtin reference counting""" _CardPool = weakref.WeakValueDictionary() """Flyweight implementation. If the object exists in the pool just return it (instead of creating a new one)""" def __new__(cls, value, suit): obj = Card._CardPool.get(value + suit, None) if not obj: obj = object.__new__(cls) Card._CardPool[value + suit] = obj obj.value, obj.suit = value, suit return obj # def __init__(self, value, suit): # self.value, self.suit = value, suit def __repr__(self): return "<Card: %s%s>" % (self.value, self.suit) if __name__ == '__main__': # comment __new__ and uncomment __init__ to see the difference c1 = Card('9', 'h') c2 = Card('9', 'h') print(c1, c2) print(c1 == c2) print(id(c1), id(c2))
点击run it 运行之!!!