#!/usr/bin/env python
# -*- coding:utf-8 -*-
__author__ = 'Andy'
'''
大話設計模式
用任意一種面向對象語言實現一個計算器控制臺程序。要求輸入兩個數和運算符號，得到結果
設計模式——簡單工廠模式
簡單工廠模式(Simple Factory Pattern):是通過專門定義一個類來負責創建其他類的實例，被創建的實例通常都具有共同的父類。
'''
class Operation(object):
  '''
  四則運算的父類,接收用戶輸入的數值
  '''
  def __init__(self, number1=0, number2=0):
    self.num1 = number1
    self.num2 = number2
  def GetResult(self):
    pass
  pass
#加法運算類
class OperationAdd(Operation):
  def GetResult(self):
    return self.num1 + self.num2
#減法運算類
class OperationSub(Operation):
  def GetResult(self):
    return self.num1 - self.num2
#乘法運算類
class OperationMul(Operation):
  def GetResult(self):
    return self.num1 * self.num2
#除法運算類
class OperationDiv(Operation):
  def GetResult(self):
    if self.num2 == 0:
      return '除數不能為0 '
    return 1.0*self.num1 / self.num2
#其他操作符類
class OperationUndef(Operation):
  def GetResult(self):
    return '操作符錯誤'
#簡單工廠類
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('請輸入第一個數值: ')
    oper = str(raw_input('請輸入一個四則運算符: '))
    num2 = input('請輸入第二個數值: ')
    # Operation(num1,num2)
    OF = OperationFactory()
    oper_obj = OF.choose_oper(oper)
    oper_obj.num1 = num1
    oper_obj.num2 = num2
    print '運算結果為: ',oper_obj.GetResult()