day12装饰器进阶

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)


# 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))
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2.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)
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3.wraps

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
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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
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转载自www.cnblogs.com/xingqisan/p/10712556.html
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