Python 设计模式 - 享元模式

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  简述

  享元模式属于结构设计模式类别。它提供了一种减少对象计数的方法。它包括有助于改进应用程序结构的各种功能。享元对象最重要的特征是不可变的。这意味着一旦构建它们就无法修改。该模式使用 HashMap 来存储引用对象。
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  如何实现享元模式？

  以下程序有助于实现享元模式 -

  
  class ComplexGenetics(object):
     def __init__(self):
        pass
     
     def genes(self, gene_code):
        return "ComplexPatter[%s]TooHugeinSize" % (gene_code)
  class Families(object):
     family = {}
     
     def __new__(cls, name, family_id):
        try:
           id = cls.family[family_id]
        except KeyError:
           id = object.__new__(cls)
           cls.family[family_id] = id
        return id
     
     def set_genetic_info(self, genetic_info):
        cg = ComplexGenetics()
        self.genetic_info = cg.genes(genetic_info)
     
     def get_genetic_info(self):
        return (self.genetic_info)
  def test():
     data = (('a', 1, 'ATAG'), ('a', 2, 'AAGT'), ('b', 1, 'ATAG'))
     family_objects = []
     for i in data:
        obj = Families(i[0], i[1])
        obj.set_genetic_info(i[2])
        family_objects.append(obj)
     
     for i in family_objects:
        print "id = " + str(id(i))
        print i.get_genetic_info()
     print "similar id's says that they are same objects "
  if __name__ == '__main__':
     test()
  

  输出

  上述程序生成以下输出 -