Python Design Patterns 简明教程

Python Design Patterns - Flyweight

享元模式属于结构设计模式类别。它提供了一种减少对象数量的方法。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点是不变的。这意味着创建后它们不能被修改。该模式使用 HashMap 来存储引用对象。

The flyweight patterb comes under the structural design patterns category. It provides a way to decrease object count. It includes various features that help in improving application structure. The most important feature of the flyweight objects is immutable. This means that they cannot be modified once constructed. The pattern uses a HashMap to store reference objects.

How to implement the flyweight pattern?

以下程序有助于实现享元模式 −

The following program helps in implementing the flyweight pattern −

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()

Output

上述程序生成以下输出 −

The above program generates the following output −

flyweight pattern