简单工厂模式

 1 class Operation(object):
 2     def __init__(self, op1,op2):
 3         self.op1 = op1
 4         self.op2 = op2
 5 
 6     def GetResult():
 7         pass
 8 
 9 class Add(Operation):
10     def GetResult(self):
11         return self.op1+self.op2
12 class Sub(Operation):
13     def GetResult(self):
14         return self.op1-self.op2
15 class Mul(Operation):
16     def GetResult(self):
17         return self.op1*self.op2
18 class Div(Operation):
19     def GetResult(self):
20         try:
21            return self.op1/self.op2
22         except:
23             print ‘divided by zero!‘
24             return 0
25 class undef(Operation):
26     def GetResult(self):
27         print ‘undefine operation‘
28         return 0
29 
30 class OperationFactory(object):
31     def CreateOperation(self,operation,op1,op2):
32         self.operations = {
33                     ‘+‘:Add(op1,op2),
34                     ‘-‘:Sub(op1,op2),
35                     ‘*‘:Mul(op1,op2),
36                     ‘/‘:Div(op1,op2)
37                     }
38         if operation in self.operations.keys():
39             return self.operations[operation]
40         else:
41             return undef(op1,op2)
42 
43 if __name__==‘__main__‘:
44     factory = OperationFactory()
45     operation = factory.CreateOperation(‘+‘,1,2)
46     print operation.GetResult()
47 
48     operation = factory.CreateOperation(‘-‘,1,2)
49     print operation.GetResult()
50 
51     operation = factory.CreateOperation(‘*‘,1,2)
52     print operation.GetResult()
53 
54     operation = factory.CreateOperation(‘/‘,1,2)
55     print operation.GetResult()
56 
57     operation = factory.CreateOperation(‘#‘,1,2)
58     print operation.GetResult()