# 1.编写装饰器,为多个函数加上认证的功能(用户的账号密码来源于文件),
# 要求登录成功一次,后续的函数都无需再输入用户名和密码
FLAG = False def login(func): def inner(*args,**kewargs): global FLAG if FLAG: ret = func(*args,**kewargs) return ret else: username = input('username: ') password = input('password: ') if username == 'tim' and password == 'cisco': FLAG = True ret = func(*args,**kewargs) return ret else: print('登录失败') return inner @login def shoplist_add(): print('增加一件物品') @login def shoplist_del(): print('删除一件物品') shoplist_add() shoplist_del()
# 2.编写装饰器,为多个函数加上记录调用功能,要求每次调用函数都将被调用的函数名称写入文件
def log(func): def inner(*args,**kwargs): with open('log',mode='a',encoding='utf-8') as f: f.write(func.__name__+'\n') ret = func(*args,**kwargs) return ret return inner @log #shoplist_add=log(shoplist_add) def shoplist_add(): print('增加一件物品') @log def shoplist_del(): print('删除一件物品') shoplist_add() shoplist_del() shoplist_add() shoplist_del() shoplist_del()
# 进阶作业(选做):
# 1.编写下载网页内容的函数,要求功能是:用户传入一个url,函数返回下载页面的结果
# 2.为题目1编写装饰器,实现缓存网页内容的功能:
# 具体:实现下载的页面存放于文件中,如果文件内有值(文件大小不为0),就优先从文件中读取网页内容,否则,就去下载,然后存到文件中
from urllib.request import urlopen import os from urllib.request import urlopen def cache(func): def inner(*args,**kwargs): if os.path.getsize('web_cache'): #不等于0就会读文件,等于0就会执行写 with open('web_cache','rb') as f: return f.read() ret = func(*args,**kwargs) #get with open('web_cache','wb') as f: f.write(b'***********'+ret) return ret return inner @cache def get(url): code = urlopen(url).read() return code ret = get('http://www.baidu.com/') print(ret) ret = get('http://www.baidu.com/') print(ret) ret = get('http://www.baidu.com/') print(ret)