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

1 class OperationBase():

2     """

3     基础运算类

4     """

5     result = 0

6     def GetResult(self):

7         return self.result

继承类

 1 class OperationAdd(OperationBase):

 2     """

 3     加法类，继承基础运算类

 4     """

 5     def __init__(self,numA,numB):

 6         self.result = numA + numB

 7     def GetResult(self):

 8         return self.result

 9 

10 class OperationSub(OperationBase):

11     """

12     减法运算类，继承基础运算类

13     """

14     def __init__(self,numA,numB):

15         self.result = numA - numB

16     def GetResult(self):

17         return self.result

18 

19 class OperationMult(OperationBase):

20     """

21     乘法运算类，继承基础运算类

22     """

23     def __init__(self,numA,numB):

24         self.result = numA * numB

25     def GetResult(self):

26         return self.result

27 

28 class OperationDiv(OperationBase):

29     """

30     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

31     """

32     def __init__(self,numA,numB):

33         try:

34             self.result = numA / numB

35         except ZeroDivisionError:

36             print "除数不能为0！！！"

37 

38     def GetResult(self):

39         return self.result

40 

41 #工厂类

42 class OperationFactor():

43     @staticmethod

44     def createOperate(operate,numA,numB):

45         for case in switch(operate):

46             if case('+'):

47                 oper = OperationAdd(numA,numB)

48                 break

49             if case('-'):

50                 oper = OperationSub(numA,numB)

51                 break

52             if case('*'):

53                 oper = OperationMult(numA,numB)

54                 break

55             if case('/'):

56                 oper = OperationDiv(numA,numB)

57                 break

58         return oper

59 

60 if __name__ == '__main__':

61     opt = raw_input("请输入一个运算操作符(+-*/)：")

62     try:

63         numA = float(raw_input("请输入第一个运算的数字："))

64         numB = float(raw_input("请输入第二个运算的数字："))

65     except ValueError:

66         print "输入数字不对，请重新输入！"

67         numA = float(raw_input("请输入第一个运算的数字："))

68         numB = float(raw_input("请输入第二个运算的数字："))

69 

70     oper = OperationFactor.createOperate(opt,float(numA),float(numB))

71     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