原型設計模式

原型設計模式有助於隱藏該類創建實例的複雜性,在對象的概念將與從頭創建的新對象的概念不同。

如果需要,新複製的對象可能會在屬性中進行一些更改。這種方法節省了開發產品的時間和資源。

如何實現原型模式?

現在讓我們看看如何實現原型模式。代碼實現如下 -

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()

執行上面程序,將生成以下輸出 -
原型設計模式

輸出中,使用現有的對象創建新對象,並且在上述輸出中清晰可見。

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