Python实现的购物车功能示例

#!/usr/env python#coding:utf-8import re,mathdef get_customer_salary():  while True:    salary=raw_input('Please input your monthly salary(a positive integer):')    if __is_valid_num(salary):      return int(salary)    else:      print '[warn] Please input a valid number!'def __is_valid_num(num):  p=re.compile(r'^/d+$')  m=p.match(num)  if m:    return True  else:    return Falsedef get_customer_selection():  while True:    selection=raw_input('Please enter the goods number you want to buy:')    if __is_valid_num(selection):      if __is_a_valid_selection(int(selection)):        return int(selection)      else:        print '[warn] Please enter a valid selection number'    else:      print '[warn] Please enter a valid number!/n'def __is_a_valid_selection(selection):  if 1<=selection<=get_total_amount_of_products():    return True  else:    return Falsedef get_products_list():  return {'Flower':50,'Perfume':300,'Shoes':600,'Clothing':800,'Alcohol':300,       'Makeup':800,'Bike':1500,'Car':200000,'Apartment':5000000}def get_total_amount_of_products():  return len(get_products_list())def mapping_type_code_for_products():  return ['Flower','Perfume','Shoes','Clothing','Alcohol','Makeup','Bike','Car','Apartment']def get_product_price(type_code):  return get_products_list()[get_product_name(type_code)]def get_product_name(type_code):  return mapping_type_code_for_products()[type_code-1]def get_lowest_price_of_products():  price_list=[]  for k,v in get_products_list().items():    price_list.append(v)  return min(price_list)def get_highest_price_of_produces():  price_list=[]  for k,v in get_products_list().items():    price_list.append(v)  return max(price_list)def still_can_buy_something(left_money):  if left_money<get_lowest_price_of_products():    return False  else:    return Truedef still_want_to_buy_something():  while True:    answer=raw_input('Do you still want to buy something?(y/n):')    result=is_a_valid_answer(answer)    if result=='yes':return True    if result=='no':return False    print '[warn] Please enter [yes/no] or [y/n]!/n'def is_a_valid_answer(answer):  yes_pattern=re.compile(r'^[Yy][Ee][Ss]$|^[Yy]$')  no_pattern=re.compile(r'^[Nn][Oo]$|^[Nn]$')  if yes_pattern.match(answer):return 'yes'  if no_pattern.match(answer):return 'no'  return Falsedef show_shopping_list():  counter=1  for i in mapping_type_code_for_products():    print '''''(%d) %s: %s RMB''' % (counter,i+' '*(10-len(i)),str(get_products_list()[i]))    counter+=1def is_affordable(left_money,product_price):  if left_money>=product_price:    return True  else:    return Falsedef time_needed_to_work_for_buying_products(salary,price):  result=float(price)/salary  return get_formatting_time(int(math.ceil(result)))def get_formatting_time(months):  if months<12:return ('%d months' % months)  years=months/12  months=months%12  return ('%d years,%d months' % (years,months))#主程序从这里开始if __name__=='__main__':  salary=get_customer_salary() #获取月工资  total_money=salary  shopping_cart=[] #初始化购物车  while True:    show_shopping_list() #打印购物列表    #判断剩余资金是否能够购买列表中的最低商品    if still_can_buy_something(total_money):      selection=get_customer_selection() #获取用户需要购买的商品编号      product_price=get_product_price(selection)#获取商品的价格      product_name=get_product_name(selection)#获取商品的名称      if total_money>=product_price:        total_money-=product_price        #打印购买成功信息        print 'Congratulations!You bought a %s successfully!/n' % product_name        shopping_cart.append(product_name)#将商品加入购物车        print 'You still have %d RMB left/n' % total_money #打印剩余资金        #判断是否还想购买其他商品        if not still_want_to_buy_something():          print 'Thank you for coming!'          break      else:        #输出还需要工作多久才能购买        format_time=time_needed_to_work_for_buying_products(salary,product_price-total_money)        print 'Sorry,you can not afford this product!/n'        print "You have to work '%s' to get it!/n" % format_time        #判断是否还想购买其他商品        if not still_want_to_buy_something():break    else:      print 'Your balance is not enough and can not continue to buy anything.'      break  #打印购物车列表  print 'Now,your balance is %d,and/nYou have buy %s' % (total_money,shopping_cart)