Python实现的购物车功能示例

#!/usr/env python
#coding:utf-8
import re,math
def 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+$')
  m=p.match(num)
  if m:
    return True
  else:
    return False
def get_customer_selection():
  while True:
    selection=raw_input('Please enter the goods number you want to buy:')
    if __is_valid_num(selection):
      if __is_a_valid_selection(int(selection)):
        return int(selection)
      else:
        print '[warn] Please enter a valid selection number'
    else:
      print '[warn] Please enter a valid number!\n'
def __is_a_valid_selection(selection):
  if 1<=selection<=get_total_amount_of_products():
    return True
  else:
    return False
def get_products_list():
  return {'Flower':50,'Perfume':300,'Shoes':600,'Clothing':800,'Alcohol':300,
       'Makeup':800,'Bike':1500,'Car':200000,'Apartment':5000000}
def get_total_amount_of_products():
  return len(get_products_list())
def mapping_type_code_for_products():
  return ['Flower','Perfume','Shoes','Clothing','Alcohol','Makeup','Bike','Car','Apartment']
def get_product_price(type_code):
  return get_products_list()[get_product_name(type_code)]
def get_product_name(type_code):
  return mapping_type_code_for_products()[type_code-1]
def get_lowest_price_of_products():
  price_list=[]
  for k,v in get_products_list().items():
    price_list.append(v)
  return min(price_list)
def get_highest_price_of_produces():
  price_list=[]
  for k,v in get_products_list().items():
    price_list.append(v)
  return max(price_list)
def still_can_buy_something(left_money):
  if left_money<get_lowest_price_of_products():
    return False
  else:
    return True
def still_want_to_buy_something():
  while True:
    answer=raw_input('Do you still want to buy something?(y/n):')
    result=is_a_valid_answer(answer)
    if result=='yes':return True
    if result=='no':return False
    print '[warn] Please enter [yes/no] or [y/n]!\n'
def is_a_valid_answer(answer):
  yes_pattern=re.compile(r'^[Yy][Ee][Ss]$|^[Yy]$')
  no_pattern=re.compile(r'^[Nn][Oo]$|^[Nn]$')
  if yes_pattern.match(answer):return 'yes'
  if no_pattern.match(answer):return 'no'
  return False
def 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+=1
def is_affordable(left_money,product_price):
  if left_money>=product_price:
    return True
  else:
    return False
def 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)