python第十二课

#复习
#作业
#装饰器的进阶
    #functools.wraps
    #带参数的装饰kkd
    #多个装饰器装饰同一个函数
#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,在函数前后添加功能
#装饰器的本质:闭包函数
# 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 '爱你启丽'
#
# print(holiday.__name__)
# print(holiday.__doc__)
# ret=holiday(3) #inner
# print(set)
#
# # def outer(*args,**kwargs):
# #     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))
#
# #1.编写装饰器,为多个函数加上认证的功能(用户的帐号密码来源于文件),
# #要求登陆成功一次,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
#         '''登陆程序'''
#         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 == '222222':
#                 FLAG=True
#                 ret=func(*args,**kwargs) # func是被装饰的函数
#                 return ret
#             else:
#                 print('登陆失败')
#     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()

#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
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: #判断文件中是否有内容
                return f.read()
        ret=func(*args,**kwargs) #get() 请求网页
        with open('web_cache','wb') as f: #将请求的结果写到文件里
            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)

#生成器函数
# def generator():
#     print(1)
#     return 'a'
# ret = generator()
# print(ret)

#只要含有yield关键字的函数都是生成器的函数
#yield 不能和return工用且需要写在函数内
# def generator():
#     print(1)
#     yield 'a'
# #生成器函数:执行之后会得到一个生成器作为返回值
# ret = generator()
# print(ret)
# print(ret.__next__())

# def generator():
#     print(1)
#     yield 'a'
#     print(2)
#     yield 'b'
# g=generator()
# for i in g:
#     print(i)
# ret=g.__next__()
# print(ret)
# ret=g.__next__()
# print(ret)

#娃哈哈%i
# def wahaha():
#     for i in range(100):
#         yield '娃哈哈%s'%i
#
# g=wahaha()
# count=0
# for i in g:
#     count +=1
#     print(i)
#     if count>50:
#         break
# #print('*******',g.__next__())
# count=0
# for i in g:
#     count +=1
#     print(i)
#     if count>100:
#         break

#带参数的装饰器
#500个函数
import time
FLAG=True
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(FLAG)
@timmer_out(FLAG) #wahaha=timmer(wahaha)
def wahaha():
    time.sleep(0.1)
    print('wahawaha')
@timmer_out(FLAG)
def erguotou():
    time.sleep(0.1)
    print('ergoutoutoutotu')

wahaha()
erguotou()

def tail(filename):
    f=open('file',encoding='utf-8')
    while True:
        line=f.readline()
        if line.strip():
            yield line.strip()
g=tail('file')
for i in g:
    if '启丽' in i:
        print('我喜欢',i)

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