day12 装饰器的进阶
1复习
# 复习 # 讲作业 # 装饰器的进阶 # functools.wraps # 带参数的装饰器 # 多个装饰器装饰同一个函数 # 周末的作业 # 文件操作 # 字符串处理 # 输入输出 # 流程控制 # 装饰器 # 开发原则 : 开放封闭原则 # 装饰器的作用 :在不改变原函数的调用方式的情况下,在函数的前后添加功能 # 装饰器的本质 : 闭包函数 # def wrapper(func): # def inner(*args,**kwargs): # print('在被装饰的函数执行之前做的事') # ret = func(*args,**kwargs) # print('在被装饰的函数执行之后做的事') # return ret # return inner # # @wrapper #holiday = wrapper(holiday) # def holiday(day): # print('全体放假%s天'%day) # return '好开心' # # ret = holiday(3) # print(ret) # 接收的时候聚合 执行的时候打散 # def outer(*args): # print(args) # print(*args) # def inner(*args): # print('inner : ',args) # inner(*args) # outer(1,2,3,4) #==outer(*[1,2,3,4]) #==outer(*(1,2,3,4))
2wraps 完美装饰器
from functools import wraps def wrapper(func): #func = holiday @wraps(func) def inner(*args,**kwargs): print('在被装饰的函数执行之前做的事') ret = func(*args,**kwargs) print('在被装饰的函数执行之后做的事') return ret return inner @wrapper #holiday = wrapper(holiday) def holiday(day): '''这是一个放假通知''' print('全体放假%s天'%day) return '好开心' print(holiday.__name__) print(holiday.__doc__) ret = holiday(3) #inner print(ret) # def wahaha(): # ''' # 一个打印娃哈哈的函数 # :return: # ''' # print('娃哈哈') # print(wahaha.__name__) #查看字符串格式的函数名 # print(wahaha.__doc__) #document
3作业
# 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,**kwargs): # global FLAG # '''登录程序''' # if FLAG: # ret = func(*args, **kwargs) # func是被装饰的函数 # return ret # else: # username = input('username : ') # password = input('password : ') # if username == 'boss_gold' and password == '22222': # FLAG = True # ret = func(*args,**kwargs) #func是被装饰的函数 # 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','a',encoding='utf-8') as f: # f.write(func.__name__+'\n') # ret = func(*args,**kwargs) # return ret # return inner # # @log # 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_del() # shoplist_del() # 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 import os from urllib.request import urlopen def cache(func): def inner(*args,**kwargs): if os.path.getsize('web_cache'): 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 # {'网址':"文件名"} ret = get('http://www.baidu.com') print(ret) ret = get('http://www.baidu.com') print(ret) ret = get('http://www.baidu.com') print(ret)
4装饰器进阶
#带参数的装饰器 #500个函数 # import time # FLAGE = False # def timmer_out(flag): # def timmer(func): # def inner(*args,**kwargs): # if flag: # start = time.time() # ret = func(*args,**kwargs) # end = time.time() # print(end-start) # return ret # else: # ret = func(*args, **kwargs) # return ret # return inner # return timmer # # timmer = timmer_out(FLAGE) # @timmer_out(FLAGE) #wahaha = timmer(wahaha) # def wahaha(): # time.sleep(0.1) # print('wahahahahahaha') # # @timmer_out(FLAGE) # def erguotou(): # time.sleep(0.1) # print('erguotoutoutou') # wahaha() # erguotou() #多个装饰器装饰一个函数 def wrapper1(func): def inner1(): print('wrapper1 ,before func') ret = func() print('wrapper1 ,after func') return ret return inner1 def wrapper2(func): def inner2(): print('wrapper2 ,before func') ret = func() print('wrapper2 ,after func') return ret return inner2 def wrapper3(func): def inner3(): print('wrapper3 ,before func') ret = func() print('wrapper3 ,after func') return ret return inner3 @wrapper3 @wrapper2 @wrapper1 def f(): print('in f') return '哈哈哈' print(f()) #记录用户的登录情况 #计算这个函数的执行时间