商城购物系统
上节采用面向过程的方法实现了一个简单购物系统。在本节的项目实战中，采用面向对象的程序设计方法对上节的购物系统进行优化。
完整源码
# __author__ = 薯条老师
"""
所有回调函数都遵循相同的接口规范，读者在实际开发中，可以将回调函数作为业务层的代码
分离到其它文件
"""
def show(goods, flag = 0):
"""
:param goods: goods table, e.g:{
1: {"name": "洗发水", "price": 22},
2: {"name": "牙膏", "price": 15},
}, or [{"id": 1, "name": "洗发水", "price": 22}, ]
:return:
"""
tr = "+"+"-"*5+"+"+"-"*16+"+"+"-"*10+"+"
heading = "|{:^5s}|{:^13s}|{:^8s}|".format("id", "商品名", "售价")
print(tr+"\n"+heading+"\n"+tr)
if flag == 0:
for id_ in goods:
print("|{0:^5s}|{1:{3}^8s}|{2:^10s}|".format(str(id_), goods[id_]["name"],
str(goods[id_]["price"]), chr(12288)))
else:
for item in goods:
print("|{0:^5s}|{1:{3}^8s}|{2:^10s}|".format(str(item["id"]), item["name"],
str(item["price"]), chr(12288)))
print(tr)
class ShowGoodsHandler:
__instance = None
def __call__(self, chipscoco):
print("以下是商城中的所有商品:")
show(chipscoco["goods"])
@classmethod
def get_instance(cls):
if cls.__instance is None:
cls.__instance = ShowGoodsHandler()
return cls.__instance
class ChipsCoco:
def __init__(self, data):
self.__data = data
self.__handlers = {}
self.__begin_prompt = "您好，欢迎使用薯条橙子在线购物系统chipscoco，输入<>中的指令来使用购物系统:\n"
self.__end_prompt = "<quit>:退出系统\n请输入指令:____\b\b\b\b"
self.__prompts = []
self.__exit_commands = {"quit", "exit", "退出"}
self.__handler_index = 1
def __obtain_user_command(self, prompt):
command, valid = "quit",True
try:
command = input(prompt)
_ = self.__handlers[int(command)]
except (ValueError, KeyError):
command = command.lower()
if command != "quit":
command = None
valid = False
return command, valid
def add_handler(self, handler, prompt):
self.__handlers[self.__handler_index] = handler.get_instance()
self.__handler_index +=1
self.__prompts.append(prompt)
def __generate_prompt(self):
prompt = self.__begin_prompt
"""
0, 查看所有商品
1, 排序所有商品
"""
for index, value in enumerate(self.__prompts):
prompt += "<{}>:{}\n".format(index+1, value)
prompt += self.__end_prompt
return prompt
def serve_forever(self):
prompt = self.__generate_prompt()
while True:
command, valid = self.__obtain_user_command(prompt)
if not valid:
print("你输入了非法的指令!")
continue
if command in self.__exit_commands:
break
self.__handlers[int(command)](self.__data)
input("按下键盘任意键，继续使用该系统...")
if __name__ == "__main__":
chipscoco = {
"goods": {
1: {"name": "洗发水", "price": 22},
2: {"name": "牙膏", "price": 15},
3: {"name": "宠物绳", "price": 29},
4: {"name": "面包", "price": 16},
5: {"name": "啤酒", "price": 8},
6: {"name": "咖啡", "price": 30},
},
"shopping_cart": {}
}
chipscoco = ChipsCoco(chipscoco)
chipscoco.add_handler(ShowGoodsHandler, "查看所有商品")
chipscoco.serve_forever()程序的输出界面
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