王二学习python的笔记以及记录，如有雷同，那也没事，欢迎交流，wx：wyb199594
复习
1.装饰器
开发原则：开放封闭原则
作用：不改变原函数的调用方式，为函数前后扩展功能
本质：闭包函数
from functools import wraps
def wrapper(f):
@wraps(f)
def inner(*args, **kwargs):
增加功能语句
ret = f(*args, **kwargs)
return ret
return inner
@wrapper
学习内容
装饰器进阶
1.functool.wraps
2.带参数的装饰器
* 接收聚合；传递打散
多个装饰器装饰同一个函数
代码区
1. 装饰器
def outer(*args):
print(args)
print(*args) def inner(*args):
print('inner', args)
inner(*args) outer(1, 2, 3, 4) # (* 接收聚合；传递打散)
2.带参数的装饰器
from functools import wraps
import time
flag = False
def timer_out(flag):
def wrapper(f):
@wraps(f)
def inner(*args, **kwargs):
if flag:
start = time.time()
ret = f(*args, **kwargs)
end = time.time()
print(end - start)
return ret
else:
ret = f(*args, **kwargs)
return ret
return inner
return wrapper @timer_out(flag)
def wahaha():
time.sleep(0.01)
print('娃哈哈') # wahaha = wrapper(wahaha) wahaha()
print(wahaha.__name__)
3.多个装饰器装饰一个函数
def wrapper1(func): # func-----f
def inner1():
print('wrapper1_before')
func()
print('wrapper1_after')
return inner1 def wrapper2(func): # inner1
def inner2():
print('wrapper_2_before')
func()
print('wrapper2_after')
return inner2 @wrapper2 # f = wrapper2(f) f----inner2
@wrapper1 # f = wrapper1(f) f----inner1
def f():
print('in f') f()
4.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 = True
c = 1 def outer(flag):
def wrapper(f):
def inner(*args, **kwargs):
global c
li = []
with open('log', 'r', encoding='utf-8') as f1:
for line in f1:
li.append(line)
li[0] = li[0].strip()
if flag and c:
user_acc = input('请输入账号')
user_ans = input('请输入密码')
if user_acc == li[0] and user_ans == li[1]:
print('认证成功,执行函数')
ret = f(*args, **kwargs)
c = 0
return ret
else:
print('认证失败，返回')
else:
ret = f(*args, **kwargs)
return ret
return inner
return wrapper
@outer(Flag)
def wahaha():
print('娃哈哈函数体')
@outer(Flag)
def qqxing():
print('QQ星函数体') wahaha()
qqxing()
'''
# 老师答案
'''
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 == '':
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()
5.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
'''
from functools import wraps
def wrapper(f):
@wraps(f)
def inner(*args,**kwargs):
li = []
ret = f(*args,**kwargs)
with open('log1','r',encoding='utf-8') as f1, open('log1.bak','w',encoding='utf-8') as f2:
for line in f1:
li.append(line)
li.append(inner.__name__)
f2.writelines(li)
import os
os.remove('log1')
os.rename('log1.bak', 'log1')
return ret
return inner
@wrapper
def wahaha():
print('娃哈哈函数体')
@wrapper
def qqxing():
print('QQ星函数体') wahaha()
qqxing()
'''
# 老师答案
'''
# 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()
'''
6.# 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)
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)