Python之简单工厂模式实现

最近又看了下大话设计模式，决定用Python来试着实现下。

基础类

 class OperationBase():
     """
     基础运算类
     """
     result = 0
     def GetResult(self):
         return self.result

继承类

 class OperationAdd(OperationBase):
     """
     加法类，继承基础运算类
     """
     def __init__(self,numA,numB):
         self.result = numA + numB
     def GetResult(self):
         return self.result

 class OperationSub(OperationBase):
     """
     减法运算类，继承基础运算类
     """
     def __init__(self,numA,numB):
         self.result = numA - numB
     def GetResult(self):
         return self.result

 class OperationMult(OperationBase):
     """
     乘法运算类，继承基础运算类
     """
     def __init__(self,numA,numB):
         self.result = numA * numB
     def GetResult(self):
         return self.result

 class OperationDiv(OperationBase):
     """
     除法运算类，继承基础运算类，通过被除数为0异常捕获控制被除数不能为0
     """
     def __init__(self,numA,numB):
         try:
             self.result = numA / numB
         except ZeroDivisionError:
             print "除数不能为0！！！"

     def GetResult(self):
         return self.result

 #工厂类
 class OperationFactor():
     @staticmethod
     def createOperate(operate,numA,numB):
         for case in switch(operate):
             if case('+'):
                 oper = OperationAdd(numA,numB)
                 break
             if case('-'):
                 oper = OperationSub(numA,numB)
                 break
             if case('*'):
                 oper = OperationMult(numA,numB)
                 break
             if case('/'):
                 oper = OperationDiv(numA,numB)
                 break
         return oper

 if __name__ == '__main__':
     opt = raw_input("请输入一个运算操作符(+-*/)：")
     try:
         numA = float(raw_input("请输入第一个运算的数字："))
         numB = float(raw_input("请输入第二个运算的数字："))
     except ValueError:
         print "输入数字不对，请重新输入！"
         numA = float(raw_input("请输入第一个运算的数字："))
         numB = float(raw_input("请输入第二个运算的数字："))

     oper = OperationFactor.createOperate(opt,float(numA),float(numB))
     print "Result = ",oper.GetResult()

里面的case可以参考我另外一篇博客

http://www.cnblogs.com/ListenWind/p/4267517.html