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"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)