python策略模式

from abc import ABC,abstractmethod

from collections import namedtuple

##############商品类##############
class Item:
    def __init__(self,name,price,num):
        self.name = name
        self.price = price
        self.num = num

    def total(self):
        return self.price * self.num


############订单类###############
class Order:

    def __init__(self,customer,promotion=None):
        self.cart = []
        self.customer = customer
        self.promotion = promotion

    def add_to_cart(self,*items):
        for item in items:
            self.cart.append(item)

    def total(self):
        total = 0
        for item in self.cart:
            total += item.total()
        return total

    def due(self):
        if not self.promotion:
            discount = 0
        else:
            discount = self.promotion.discount(self)
        return (self.total()-discount)


#################折扣策略类###################
class Promotion(ABC):
    @abstractmethod
    def discount(self,order):
        pass

class FidelityPromo(Promotion):
    """
    如果积分满100分，就可以兑换10元现金券
    """
    def discount(self,order):
        return 10 if order.customer.fidelity > 1000 else 0

class BulkItemPromo(Promotion):
    """
    如果单件商品购买10件，即可9折
    """
    def discount(self,order):
        discount = 0
        for item in order.cart:
            if item.num >=10:
                discount += item.total() * 0.1
        return discount

class LargeOrderPromo(Promotion):
    """
    如果订单总金额大于等于500，就减50
    """
    def discount(self,order):
        discount = 0
        if order.total()>=500:
            discount = 50
        return discount


###############最优策略类#############
class BestPromo(Promotion):
    def discount(self, order):
        # 找出当前文件中所有的策略
        all_promotion = [globals()[name] for name in globals() if name.endswith('Promo') and name != 'BestPromo']

        # 计算最大折扣
        return max([promo().discount(order) for promo in all_promotion])

#############消费者############
Customer = namedtuple('Customer','name fidelity')

if __name__ == '__main__':
    xm = Customer('xiaoming',1500)
    item1 = Item('鞋',200,3)
    item2 = Item('衣服',400,1)
    order = Order(xm,FidelityPromo())
    order.add_to_cart(item1,item2)
    # print(order.total())
    # print(order.due())

    xh = Customer('xiaohong',300)
    item3 = Item('盐',10,10)
    item4 = Item('油',50,10)
    item5 = Item('米',70,2)

    order = Order(xh,BestPromo())
    order.add_to_cart(item3,item4,item5)
    print(order.total())
    print(order.due())