Python设计模式之简单工厂模式实例详解

 #!/usr/bin/env python # -*- coding:utf-8 -*- __author__ = 'Andy' ''' 大话设计模式 用任意一种面向对象语言实现一个计算器控制台程序。要求输入两个数和运算符号，得到结果 设计模式――简单工厂模式 简单工厂模式(Simple Factory Pattern):是通过专门定义一个类来负责创建其他类的实例，被创建的实例通常都具有共同的父类。 ''' class Operation(object): ''' 四则运算的父类,接收用户输入的数值 ''' def __init__(self, number1=0, number2=0): self.num1 = number1 self.num2 = number2 def GetResult(self): pass pass #加法运算类 class OperationAdd(Operation): def GetResult(self): return self.num1 + self.num2 #减法运算类 class OperationSub(Operation): def GetResult(self): return self.num1 - self.num2 #乘法运算类 class OperationMul(Operation): def GetResult(self): return self.num1 * self.num2 <strong style="color:transparent">来源gaodaima#com搞(代@码网</strong>#除法运算类 class OperationDiv(Operation): def GetResult(self): if self.num2 == 0: return '除数不能为0 ' return 1.0*self.num1 / self.num2 #其他操作符类 class OperationUndef(Operation): def GetResult(self): return '操作符错误' #简单工厂类 class OperationFactory(object): def choose_oper(self,ch): if ch == '+': return OperationAdd() elif ch == '-': return OperationSub() elif ch == '*': return OperationMul() elif ch == '/': return OperationDiv() else: return OperationUndef() if __name__ == "__main__": ch = '' while not ch == 'q': num1 = input('请输入第一个数值: ') oper = str(raw_input('请输入一个四则运算符: ')) num2 = input('请输入第二个数值: ') # Operation(num1,num2) OF = OperationFactory() oper_obj = OF.choose_oper(oper) oper_obj.num1 = num1 oper_obj.num2 = num2 print '运算结果为: ',oper_obj.GetResult()