购物车程序优化2

前几天写的购物代码觉得特别冗余，而且可操作性不强，很容易出错，今天做如下简化，好用多了。
 1 # -*- coding:utf-8 -*-
 2 # __Author__ : "110"
 3 # date:2018/12/27
 4 salary = 5000
 5 
 6 shop_list = [('iphone',9000),('mac book',10000),('python book',90),('coffee',32),
 7              ('bicycle',1500)]
 8 
 9 money = input("请输入您的现金总数：")
10 money = int(money)
11 have_buy_commodity = []
12 while True:
13     for i, v in enumerate(shop_list, 1):
14         print(i, v)
15 
16     query_buy_shop = input("请输入要购买的商品编号，q[退出]：")
17 
18     if query_buy_shop.isdigit():
19         query_buy_shop = int(query_buy_shop)
20 
21         if query_buy_shop >=1 and query_buy_shop <=5:
22             spend_money = shop_list[query_buy_shop-1]
23             buy_commodity = shop_list[query_buy_shop-1][0]
24             money = money - spend_money[1]
25 
26             if money < 0:
27                 print("您的余额不足,无法购买此商品！")
28                 print('--------Shop List--------')
29                 print(have_buy_commodity)
30                 print('--------------------------')
31                 break
32             else:
33                 have_buy_commodity.append(buy_commodity)
34                 print("您的余额为%s元!" % money)
35 
36     elif query_buy_shop == 'q':
37         print("已退出购物系统！")
38         print("您的余额为%s元!" % money)
39         print('--------Shop List--------')
40         print(have_buy_commodity)
41         print('--------------------------')
42         break
43 
44     else:
45         print("输入的字符非法,请重新选择!")
代码解析：