Python之簡單工廠模式實現

最近又看了下大話設計模式，決定用Python來試着實現下。

基礎類

1 class OperationBase():
2     """
3     基礎運算類
4     """
5     result = 0
6     def GetResult(self):
7         return self.result

繼承類

 1 class OperationAdd(OperationBase):
 2     """
 3     加法類，繼承基礎運算類
 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     減法運算類，繼承基礎運算類
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     乘法運算類，繼承基礎運算類
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     除法運算類，繼承基礎運算類，經過被除數爲0異常捕獲控制被除數不能爲0
31     """
32     def __init__(self,numA,numB):
33         try:
34             self.result = numA / numB
35         except ZeroDivisionError:
36             print "除數不能爲0！！！"
37 
38     def GetResult(self):
39         return self.result
40 
41 #工廠類
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("請輸入一個運算操做符(+-*/)：")
62     try:
63         numA = float(raw_input("請輸入第一個運算的數字："))
64         numB = float(raw_input("請輸入第二個運算的數字："))
65     except ValueError:
66         print "輸入數字不對，請從新輸入！"
67         numA = float(raw_input("請輸入第一個運算的數字："))
68         numB = float(raw_input("請輸入第二個運算的數字："))
69 
70     oper = OperationFactor.createOperate(opt,float(numA),float(numB))
71     print "Result = ",oper.GetResult()

裏面的case能夠參考我另一篇博客

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