Python設(shè)計(jì)模式之簡(jiǎn)單工廠模式實(shí)例詳解

#!/usr/bin/env python
# -*- coding:utf-8 -*-
__author__ = 'Andy'
'''
大話設(shè)計(jì)模式
用任意一種面向?qū)ο笳Z言實(shí)現(xiàn)一個(gè)計(jì)算器控制臺(tái)程序。要求輸入兩個(gè)數(shù)和運(yùn)算符號(hào)，得到結(jié)果
設(shè)計(jì)模式——簡(jiǎn)單工廠模式
簡(jiǎn)單工廠模式(Simple Factory Pattern):是通過專門定義一個(gè)類來負(fù)責(zé)創(chuàng)建其他類的實(shí)例，被創(chuàng)建的實(shí)例通常都具有共同的父類。
'''
class Operation(object):
  '''
  四則運(yùn)算的父類,接收用戶輸入的數(shù)值
  '''
  def __init__(self, number1=0, number2=0):
    self.num1 = number1
    self.num2 = number2
  def GetResult(self):
    pass
  pass
#加法運(yùn)算類
class OperationAdd(Operation):
  def GetResult(self):
    return self.num1 + self.num2
#減法運(yùn)算類
class OperationSub(Operation):
  def GetResult(self):
    return self.num1 - self.num2
#乘法運(yùn)算類
class OperationMul(Operation):
  def GetResult(self):
    return self.num1 * self.num2
#除法運(yùn)算類
class OperationDiv(Operation):
  def GetResult(self):
    if self.num2 == 0:
      return '除數(shù)不能為0 '
    return 1.0*self.num1 / self.num2
#其他操作符類
class OperationUndef(Operation):
  def GetResult(self):
    return '操作符錯(cuò)誤'
#簡(jiǎn)單工廠類
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('請(qǐng)輸入第一個(gè)數(shù)值: ')
    oper = str(raw_input('請(qǐng)輸入一個(gè)四則運(yùn)算符: '))
    num2 = input('請(qǐng)輸入第二個(gè)數(shù)值: ')
    # Operation(num1,num2)
    OF = OperationFactory()
    oper_obj = OF.choose_oper(oper)
    oper_obj.num1 = num1
    oper_obj.num2 = num2
    print '運(yùn)算結(jié)果為: ',oper_obj.GetResult()