python的装饰器使用与实战

函数及“变量”，将函数当作变量传入：

import time
def bar():
    time.sleep(2)
    print ("in the bar")

def test1(func):
    start_time=time.time()
    func()    #run bar
    stop_stime=time.time()
    print ("the func run time is %s" %(stop_stime-start_time))

test1(bar)

in the bar
the func run time is 2.00496697426

实现装饰器：

1、函数及“变量”
2、高阶函数
a:把一个函数名当作实参传给另一个函数（在不修改被装饰函数源代码的情况下为其添加功能）
b:返回值中包含函数名（不修改函数的调用方式）
3、嵌套函数
高阶函数+嵌套函数=》装饰器

实例：
import time

#嵌套函数
def timer(func): #timer(test1)   func=test1
    #*args,**kwargs 这个代表不固定参数，可传参可不传参
    def deco(*args,**kwargs):
        start_time=time.time()
        func(*args,**kwargs)
        stop_stime=time.time()
        print ("the func run time is %s" %(stop_stime-start_time))
    return deco
@timer  #test1 = timer(test1)
def test1():
    time.sleep(2)
    print "in the test1"
@timer
def test2(name):
    time.sleep(2)
    print ("name:",name)


#下面操作相当于@timer,哪个函数用就在哪个函数前面加上@timer
# test1 = timer(test1)
# test1() #run deco()
# test2=timer(test2)
# test2()
test1()
test2("chao")

in the test1
the func run time is 2.00393605232
(‘name:’, ‘chao’)
the func run time is 2.00482201576

示例简单的网站验证登录：

#模拟登陆验证
user,passwd='chao','123'
def auth(auth_type):  #auth_type: 'local'
    print ("auth func:",auth_type)
    def outer_wrapper(func):
        def wrapper(*args,**kwargs):
            if auth_type=="local":
                username=raw_input("Username:").strip()
                password=raw_input("Password:").strip()
                if user==username and passwd==password:
                    print ("\033[32;1mUser has passed authentication\033[0m")
                    rex=func(*args,**kwargs)
 #                   print ("--after")
                    return rex
                else:
                    exit ("\033[31;1mInvalid username or password\033[0m")
            elif auth_type=="ldap":
                func(*args, **kwargs)
                print ("这个没搞过")

        return wrapper
    return outer_wrapper
def index():
    print ("welcome to index page")

@auth(auth_type="local") #home=auth()
def home():
    print ("welcome to home page")
    return "from home"

@auth(auth_type="ldap")
def bbs():
    print ("welcome to bbs page")

index()
#run home()相当于执行wrapper
print (home())
bbs()

(‘auth func:’, ‘local’)
(‘auth func:’, ‘ldap’)
welcome to index page
Username:chao
Password:123
User has passed authentication
welcome to home page
from home
welcome to bbs page
这个没搞过