Python装饰器

装饰器:

*  高阶函数  +  嵌套函数  =>  装饰器

<1>.：定义：本质是函数，（装饰其他函数）就是为其他函数添加新功能。

　　　　　　原则：a:不能修改被装饰的函数的源代码。

　　　　　　　　　b:不能修改被装饰的函数的调用方式。

<2>.实现装饰器的知识储备：

1：函数即变量。

2：高阶函数

　　a,把一个函数名当做实参传给另外一个函数(在不修改被装饰函数源代码的情况下为期添加新功能)。

import time
def bar():
    time.sleep(3)
    print("in the bar")

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

test1(bar)

　　b,返回值中包含函数名(不修改函数的调用方式)。

import time

def bar():
    time.sleep(3)
    print("in the bar")
    return True

def test2(func):
    print(func)
    return func

# print(test2(bar))
# print(test2(bar))
# print(test2(bar))
# test2(bar())
# bar()
# print(bar())
# t = test2(bar)
# print(t)
# t()
bar = test2(bar)
bar()

<3>.嵌套函数。

def foo():
    print("in the foo")
    def bar():
        print("in the bar")
    bar()

foo()

x=0
def grandpa():
    x=1
    def dad():
        x=2
        def son():
            x=3
            print(x)
        son()
    dad()

grandpa()

<3>.使用装饰器

import time

def deco(func):
    start_time = time.time()
    func()
    stop_time = time.time()
    print("the fun run time is %s" %(stop_time - start_time))


def test1():
    time.sleep(3)
    print("in the test1")

def test2():
    time.sleep(3)
    print("in the test2")

# test1()
# test2()
# deco(test1())  #test1的返回值
deco(test1)
deco(test2)

import time

def deco(func):
    start_time = time.time()
    return func
    stop_time = time.time()
    print("the fun run time is %s" %(stop_time - start_time))


def test1():
    time.sleep(3)
    print("in the test1")
def test2():
    time.sleep(3)
    print("in the test2")

# test1()
# test2()
# deco(test1())  #test1的返回值
# deco(test1)
# deco(test2)
test1 = deco(test1)
test1()

teat2 = deco(test2)
test2()

import time

def timer(func):
    def deco():
        start_time = time.time()
        func()
        stop_time = time.time()
        print("the fun run time is %s" %(stop_time - start_time))
    return deco

def test1():
    time.sleep(3)
    print("in the test1")
def test2():
    time.sleep(3)
    print("in the test2")

test1 = timer(test1)
test1()

test2 = timer(test2)
test2()

import time

def timer(func):
    def deco():
        start_time = time.time()
        func()
        stop_time = time.time()
        print("the fun run time is %s" %(stop_time - start_time))
    return deco

@timer     #test1 = timer(test1)
def test1():
    time.sleep(3)
    print("in the test1")

@timer    #test2 = timer(test2)
def test2():
    time.sleep(3)
    print("in the test2")

# test1 = timer(test1)
test1()
# test2 = timer(test2)
test2()

import time

def timmer(func):
    def deco():
        start_time = time.time()
        func()
        stop_time = time.time()
        print("the time run is %s" %(stop_time - start_time))
    return deco

@timmer  #test1 = timer(test1)
def test1():
    time.sleep(3)
    print("in the test1")

test1()

in the test1
the time run is 3.0006814002990723

import time

def timmer(func):
    def deco(*args, **kwargs):
        start_time = time.time()
        func(*args, **kwargs)
        stop_time = time.time()
        print("the time run is %s" %(stop_time - start_time))
    return deco

@timmer  #test1 = timer(test1)
def test1(*args, **kwargs):
    time.sleep(3)
    print("in the test1")

test1()