享元模式
定义
运用共享技术有效支持大量细粒度的对象
实例python实现!
- 注意使用WeakValueDictionary的原因是因为销掉对象,不取决于池!
- 注意单例模式!
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)
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)