1 # coding=utf-8
 2 # 简单工厂模式的介绍及代码实例
 3 # 举个加减乘除的例子
 4 # 定义一个父类，预留接口
 5 class Operation(object):
 6     def __init__(self, num1 = 0, num2 = 0):
 7         self.num1 = num1
 8         self.num2 = num2
 9 
10     # 这是一个预留的统一的接口，子类可以根据自己的情况调用这个接口，实现自己的特殊功能
11     def get_result(self):
12         pass
13 
14 
15 class Add(Operation):
16     def get_result(self):
17         return self.num1 + self.num2
18 
19 class Minus(Operation):
20     def get_result(self):
21         return self.num1 - self.num2
22 
23 class Multi(Operation):
24     def get_result(self):
25         return self.num1 * self.num2
26 
27 class Divide(Operation):
28     def get_result(self):
29         try:
30             return self.num1/self.num2
31         except:
32             return ‘被除数不能为0，请重新输入‘
33 
34 # 这个就是一个工厂，根据用户的输入选择来调用相应的类去创建实例完成任务
35 class OptionFactory():
36     def choose(self,op):
37         if op == ‘+‘:
38             return Add()
39         if op == ‘-‘:
40             return Minus()
41         if op == ‘*‘:
42             return Multi()
43         if op == ‘/‘:
44             return Divide()
45 
46 # 根据用户输入来决定调用哪个类，这就是工厂类的作用
47 if __name__ == ‘__main__‘:
48     ch = ‘‘
49     while not ch == ‘q‘:
50         num1 = eval(raw_input(‘Please input number1:  ‘))
51         op = str(raw_input(‘Please input the operation:  ‘))
52         num2 = eval(raw_input(‘Please input number2:  ‘))
53         OPFactory = OptionFactory()
54         OPType = OPFactory.choose(op)
55         OPType.num1 = num1
56         OPType.num2 = num2
57         print ‘The result is:‘, OPType.get_result()
58         try:
59             ch = str(raw_input())
60         except:
61             ch = ‘‘