python设计模式(一)--简单工厂(中)

摘要: 交互式收银计算器

最近正在持续更新源码库，代码都是参考大话设计模式翻成python版，完整代码片段请到github上去下载.
https://github.com/zhengtong0898/python-patterns
参考：

书籍<<大话设计模式>> 第二章 2.1 -- 2.3

Python 3.x

[code=plain]# -.- coding:utf-8 -.-
# __author__ = 'zhengtong'
# 知识点：面向对象的编程，并不是类越多越好，类的划分是为了封装，
#         但分类的基础是抽象，具有相同属性和功能的对象的抽象集合才是类。

_price_repr = '单价：'
_number_repr = '数量：'
_total_repr = '合计：'

class CashSuper:
"""现金收取类(抽象类)"""

def __init__(self, money):
self.money = money

def accept_cash(self):
raise NotImplementedError

class CashNormal(CashSuper):
"""正常收费子类"""

def accept_cash(self):
return self.money

class CashRebate(CashSuper):
"""打折收费子类"""

def __init__(self, rebate, **kwargs):
"""
这里为什么采用**kwargs, 请参考下面这个链接: http://my.oschina.net/zhengtong0898/blog/670917 """
super(CashRebate, self).__init__(**kwargs)
self.rebate = rebate

def accept_cash(self):
return self.money * self.rebate

class CashReturn(CashSuper):
"""返利收费子类"""

def __init__(self, condition, money_return, **kwargs):
super(CashReturn, self).__init__(**kwargs)
self.condition = int(condition)
self.money_return = int(money_return)

def accept_cash(self):
result = self.money
# 当满足了返利条件, 则采用计算规则.
if self.money >= self.condition:
result = self.money - int(self.money / self.condition) * self.money_return
return result

class CashFactory:
"""现金收费工厂类"""

@staticmethod
def create_cash_accept(typed, **kwargs):
if typed == 1:
result = CashNormal(**kwargs).accept_cash()
elif typed == 2:
result = CashReturn(300, 100, **kwargs).accept_cash()
elif typed == 3:
result = CashRebate(0.8, **kwargs).accept_cash()
else:
raise KeyError('无效的返利选择')
return result

def main():
result = 0
while True:
try:
prices = int(input(_price_repr))
number = int(input(_number_repr))
price_off = int(input('返利模式: 1(正常收费), 2(满300返100), 3(打8折)：'))
money = CashFactory.create_cash_accept(price_off, money=prices*number)
result += money
print(_price_repr, prices, _number_repr, number, _total_repr, money)
except KeyboardInterrupt:
print('')
print('oops: 检测到Ctrl + C组合键, 正在返回总费用并推出程序')
break
return result

if __name__ == '__main__':
print('温馨提示：输入Ctrl + C组合键可得到总数和退出程序.')
print(main())