一、装饰器

1. 装饰器本质是函数
2. 为其他函数添加附加功能
3. 不修改被修饰函数的源代码
4. 不修改被修饰函数的调用方式

• 装饰器示例

import timedef timmer(func):def wrapper(*args,**kwargs):start_time = time.time()res = func(*args,**kwargs)stop_time = time.time()print("函数的运行时间：%s" % (stop_time - start_time))return resreturn wrapper@timmer
def calc(l):s = 0for i in l:s += itime.sleep(0.1)return sprint(calc(range(20)))

• 装饰器示例2

import timedef timmer(func):def wrapper():start_time = time.time()func()  #运行传进来的f函数stop_time = time.time()print("函数的运行时间是： %s" % (stop_time - start_time))return wrapper@timmer  #f = timmer(f)  #将f函数传给timmer
def f():time.sleep(3)print("f 函数运行完成。")f()  #执行wrapper()

• 修饰带返回值的函数

import timedef timmer(func):def wrapper():start_time = time.time()res = func()  #运行传进来的f函数stop_time = time.time()print("函数的运行时间是： %s" % (stop_time - start_time))return res  #将f函数的返回值返回return wrapper@timmer  #f = timmer(f)  #将f函数传给timmer
def f():time.sleep(3)print("f 函数运行完成。")return "f函数的返回值"

• 修饰带参数的函数

import timedef timmer(func):def wrapper(*args,**kwargs):start_time = time.time()res = func(*args,**kwargs)  #运行传进来的f函数stop_time = time.time()print("函数的运行时间是： %s" % (stop_time - start_time))return res  #将f函数的返回值返回return wrapper@timmer  #f = timmer(f)  #将f函数传给timmer
def f(name):time.sleep(1)print("f 函数运行完成。函数的参数是：%s" %name)return "f函数的返回值"res = f("dongfei")  #执行wrapper()
print(res)

• 认证登录装饰器示例

def auth(func):def warpper(*args,**kwargs):username = input("your username: ")password = input("your password: ")if username == "dongfei" and password == "123":res = func(*args,**kwargs)return reselse:print("username or password error!")return warpperdef index():print("welcome to my index page.")@auth
def home(name):print("%s go home" %name)@auth
def shopping_car():print("your shopping_car")index()
home("dongfei")
shopping_car()

• 模拟记录session

user_list = [{"username":"dongfei", "password":"123456"},{"username":"dongfei2", "password":"123456"},{"username":"dongfei3", "password":"123456"},{"username":"dongfei4", "password":"123456"},
]current_dic = {"username":None, "login_status":False}def auth(func):def warpper(*args,**kwargs):if current_dic["username"] and current_dic["login_status"]:res = func(*args, **kwargs)return resusername = input("your username: ")password = input("your password: ")for user_dic in user_list:if username == user_dic["username"] and password == user_dic["password"]:current_dic["username"] = usernamecurrent_dic["login_status"] = Trueres = func(*args,**kwargs)return reselse:print("username or password error!")return warpperdef index():print("welcome to my index page.")@auth
def home(name):print("%s go home" %name)@auth
def shopping_car():print("your shopping_car")index()
home("dongfei")
shopping_car()

• 带参数的装饰器

user_list = [{"username":"dongfei", "password":"123456"},{"username":"dongfei2", "password":"123456"},{"username":"dongfei3", "password":"123456"},{"username":"dongfei4", "password":"123456"},
]current_dic = {"username":None, "login_status":False}def auth(auth_type):def auth_func(func):def warpper(*args,**kwargs):if auth_type == "file_db":if current_dic["username"] and current_dic["login_status"]:res = func(*args, **kwargs)return resusername = input("your username: ")password = input("your password: ")for user_dic in user_list:if username == user_dic["username"] and password == user_dic["password"]:current_dic["username"] = usernamecurrent_dic["login_status"] = Trueres = func(*args,**kwargs)return reselse:print("username or password error!")elif auth_type == "mysql_db":print("请使用%s认证：" %auth_type)else:print("无效的认证类型")return warpperreturn auth_func@auth("ldap")
def index():print("welcome to my index page.")@auth(auth_type="mysql_db")  # @auth(auth_type="mysql") 等于 @auth_func
def home(name):print("%s go home" %name)@auth(auth_type="file_db")
def shopping_car():print("your shopping_car")index()
home("dongfei")
shopping_car()

二、高阶函数

1. 函数接受的参数是一个函数名
2. 函数的返回值是一个函数名
3. 满足以上条件的任意一个都是高阶函数

import timedef foo():print("from foo")time.sleep(2)def timmer(func):start_time = time.time()func()stop_time = time.time()print("函数的运行时间：%s" % (stop_time - start_time))return funcfoo = timmer(foo)
foo()

三、解压序列

>>> a,*_,c = [1,2,3,4,5,6,7,8]  #取第一个和最后一个值
>>> a
1
>>> c
8
>>> _
[2, 3, 4, 5, 6, 7]