# -*- coding: utf-8 -*-
from abc import ABC ,abstractclassmethod
from collections import namedtuple
Customer = namedtuple('Customer','name fidelity')
class lineItem:
"""初始化明细行:产品、数量、单价"""
def \_\_init\_\_(self,product,qty,price):
self.product = product
self.qty = qty
self.price = price
def total(self):
return self.price\*self.qty
class Order:
"""客户、购物车、 促销活动"""
def \_\_init\_\_(self, customer, cart, promotion=None):
self.customer = customer
self.cart = list(cart)
self.promotion = promotion
def total(self):
"""hasattr:用法:判断是否包含对应的属性"""
if not hasattr(self,'\_\_total'):
self.\_\_total = sum(item.total() for item in self.cart) #计算购物车里总金额
return self.\_\_total
def due(self):
if self.promotion is None:
discount=0
else:
discount = self.promotion.discount(self)
return self.total()-discount
def \_\_repr\_\_(self):
fmt = '<Order total:{:.2f} due :{:.2f}>'
return fmt.format(self.total(),self.due())
class Promotion(ABC): #策略 抽象基类
"""
@abstractmethod:抽象方法,含abstractmethod方法的类不能实例化,继承了含abstractmethod方法的子类必须复写所有abstractmethod装饰的方法,未被装饰的可以不重写
@ property:方法伪装属性,方法返回值及属性值,被装饰方法不能有参数,必须实例化后调用,类不能调用
@ classmethod:类方法,可以通过实例对象和类对象调用,被该函数修饰的方法第一个参数代表类本身常用cls,被修饰函数内可调用类属性,不能调用实例属性
@staticmethod:静态方法,可以通过实例对象和类对象调用,被装饰函数可无参数,被装饰函数内部通过类名.属性引用类属性或类方法,不能引用实例属性
"""
@abstractclassmethod
def discount(self,order):
"""返回折扣金额、"""
class FidelityPromo(Promotion): #策略1
"""积分为1000或以上的客户提供5%的折扣"""
def discount(self,order):
return order.total()*0.05 if order.customer.fidelity>=1000 else 0
class BulkItemPromo(Promotion):#策略2
"""单个商品为20个或以上时提供10%的折扣"""
def discount(self,order):
discount = 0
for item in order.cart:
if item.quantity>=20:
discount+=item.total()\*0.1
return discount
class LargeOrderPromo(Promotion):#策略3
"""订单中不同商品达到10个或以上时提供7%的折扣"""
def discount(self, order):
discount\_items = {item.product for item in order.cart}
if len(discount\_items)>=10:
return order.total()\*0.07
return 0
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