Python 设计模式 - 原型模式

• 

  简述

  原型设计模式有助于隐藏类创建的实例的复杂性。现有对象的概念与从头创建的新对象的概念不同。

  如果需要，新复制的对象可能会在属性中进行一些更改。这种方法节省了用于开发产品的时间和资源。
• 

  如何实现原型模式？

  现在让我们看看如何实现原型模式。

  
  import copy
  class Prototype:
     _type = None
     _value = None
     def clone(self):
        pass
     def getType(self):
        return self._type
     def getValue(self):
        return self._value
  class Type1(Prototype):
     def __init__(self, number):
        self._type = "Type1"
        self._value = number
     def clone(self):
        return copy.copy(self)
  class Type2(Prototype):
     """ Concrete prototype. """
     def __init__(self, number):
        self._type = "Type2"
        self._value = number
     def clone(self):
        return copy.copy(self)
  class ObjectFactory:
     """ Manages prototypes.
     Static factory, that encapsulates prototype
     initialization and then allows instatiation
     of the classes from these prototypes.
     """
     __type1Value1 = None
     __type1Value2 = None
     __type2Value1 = None
     __type2Value2 = None
     @staticmethod
     def initialize():
        ObjectFactory.__type1Value1 = Type1(1)
        ObjectFactory.__type1Value2 = Type1(2)
        ObjectFactory.__type2Value1 = Type2(1)
        ObjectFactory.__type2Value2 = Type2(2)
     @staticmethod
     def getType1Value1():
        return ObjectFactory.__type1Value1.clone()
     @staticmethod
     def getType1Value2():
        return ObjectFactory.__type1Value2.clone()
     @staticmethod
     def getType2Value1():
        return ObjectFactory.__type2Value1.clone()
     @staticmethod
     def getType2Value2():
        return ObjectFactory.__type2Value2.clone()
  def main():
     ObjectFactory.initialize()
     
     instance = ObjectFactory.getType1Value1()
     print "%s: %s" % (instance.getType(), instance.getValue())
     
     instance = ObjectFactory.getType1Value2()
     print "%s: %s" % (instance.getType(), instance.getValue())
     
     instance = ObjectFactory.getType2Value1()
     print "%s: %s" % (instance.getType(), instance.getValue())
     
     instance = ObjectFactory.getType2Value2()
     print "%s: %s" % (instance.getType(), instance.getValue())
  if __name__ == "__main__":
     main()
  

  输出

  上述程序将生成以下输出 -

  

  输出有助于使用现有对象创建新对象，并且在上述输出中清晰可见。