Python核心编程第二版 第十三章课后练习 13-11 电子商务

版本：python3.7.4

"""
你需要为一家B2C(商业到消费者)零售商编写一个基础的电子商务引擎。你需要写一个针对顾客
的类User, 一个对应存货清单的类Item, 还有一个对应购物车的类叫Cart. 货物放到购物车里，
顾客可以有多个购物车。同时购物车里可以有多个货物，包括多个同样的货物。
"""
import pickle
import os
def prop(func):
    return property(**func())
class Item(object):
    def __init__(self):
        self.nm='goods.db'
        if not os.path.exists(self.nm):
            self.fhandler=open(self.nm,'wb')
            self.dict_item={}
        else:
            self.fhandler=open(self.nm,'rb')
            self.dict_item=self.get_item()
        print('items:',self.dict_item)
    def __del__(self):
        self.fhandler.close()
    def goodsVerify(self,goods,num):
        if goods in self.dict_item.keys() and num<=self.dict_item[goods]:
            return True
    def modify_item(self,item,num):
        if 0>=num:
            del self.dict_item[item]
        elif item not in self.dict_item.keys():
            self.dict_item[item]=num
        with open(self.nm,'wb') as f:
            pickle.dump(self.dict_item,f)
    def get_item(self):
        try:
            self.dict_item=pickle.load(self.fhandler)
        except Exception as e:
            print(e)
            return
        if self.dict_item is None:
            self.dict_item={}
        return self.dict_item
    def del_item(self):
        if os.path.exists(self.nm):
            os.remove(self.nm)
        else:
            print('Goods list is not existed!')
class Cart(object):
    def __init__(self,account,cart):
        self.nm='{}_{}.dbm'.format(account,cart)
        if not os.path.exists(self.nm) or 0==os.path.getsize(self.nm):
            self.fp=open(self.nm,'wb')
            self.dict_cart={}
        else:
            self.fp=open(self.nm,'rb')
            # print('size:',os.path.getsize(self.nm))
            self.dict_cart = pickle.load(self.fp)
    def toCart(self,goods,num):
        if goods not in self.dict_cart.keys():
            self.dict_cart[goods] = num
        else:
            self.dict_cart[goods]=self.dict_cart[goods]+num
        self.saveAll()
        print('%s:%s '%(self.nm,self.dict_cart))
    def modifyCart(self,goods,num):
        if 0>=num:
            pass
        else:
            self.dict_cart[goods]=num
    def delFrom(self,goods):
        if goods not in self.dict_cart.keys():
            pass
        del self.dict_cart[goods]
    def emptyCart(self):
        del self.dict_cart
    def saveAll(self):
        with open(self.nm,'wb') as f:
            pickle.dump(self.dict_cart,f)
import shelve
class User(object):
    def __init__(self,account=None,pwd=None):
        self._flag = False
        self.account=account
        self.dbm=shelve.open('user.dbm')
        if account and pwd:
            self.login(account,pwd)
    def __del__(self):
        self.dbm.close()
    def register(self,account,pwd):
        if account in list(self.dbm.keys()):
            return
        self.dbm[account]=pwd
        print('register successfully!')
        # self._flag=False
    def login(self,account,pwd):
        if not account in list(self.dbm.keys()):
            self._flag=False
            print('user [%s] is not exist.'%account)
            return
        if self.dbm[account] == pwd:
            print('login successfully!')
            self._flag=True
        else:
            self._flag=False
    def loginout(self):
        self._flag=False
    def cart(self,cart):
        if self._flag:
            account=self.account
            return Cart(account,cart)
        else:
            print('please login first!')
    def to_Cart(self,item_obj,cart_obj,goods,num=1):
        if self._flag:
            if item_obj.goodsVerify(goods,num):
                cart_obj.toCart(goods,num)
        else:
            print('please login first!')
    def modify_Cart(self,item_obj,cart_obj,goods,num):
        if self._flag:
            if item_obj.goodsVerify(goods,num):
                cart_obj.modifyCart(goods,num)
        else:
            print('please login first!')
if __name__ == '__main__':
    inventory = Item()
    inventory.modify_item('math book', 1)
    inventory.modify_item('english book', 11)
    inventory.modify_item('musci book', 21)
    goods_list = inventory.dict_item
    user_1=User('jojo','jojo')
    # user_1.register('jojo','jojo')
    print(user_1._flag)
    # user_1.login('jojo','jojo')
    cart1=user_1.cart('cart1')
    user_1.to_Cart(inventory,cart1,'math book',2)
    user_1.to_Cart(inventory, cart1, 'musci book', 2)
    cart2 = user_1.cart('cart2')
    user_1.to_Cart(inventory, cart2, 'english book', 1)

    user_2=User('haohao','haohao')
    # user_2.register('haohao','haohao')
    ucart2=user_2.cart('ucart1')
    ucart2.toCart('math book',1)

    user_3=User()
    print(user_3._flag)
    cart3=user_3.cart('cart3')
    user_3.to_Cart(inventory,cart3,'english book', 1)

运行结果：

items: {'math book': 1, 'english book': 11, 'musci book': 21}
login successfully!
True
jojo_cart1.dbm:{'math book': 6, 'musci book': 32} 
jojo_cart2.dbm:{'english book': 18} 
login successfully!
haohao_ucart1.dbm:{'math book': 7} 
False
please login first!
please login first!

生成的文件：