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#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()