python局部变量、高级函数、匿名函数、嵌套函数、装饰器

1.局部变量

在函数内部，可以用Global，显式的声明为全局变量。这种方式永远不要这么用。

Ctrl+？多行注释i

2.高级函数

把函数名当做参数，传给函数

def add(a,b,f):

return f(a)+f(b)

res = add(3,-6,abs)

abs是内置函数

def bar():

print("in the bar")

def test1(func):

首先看第一个例子：def bar():

print("in the bar")

def test1(func):

print(func)

func()

test1(bar)

<function bar at 0x0000019A43BC2E18>
in the bar

其次看第二个例子：

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

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

test1(bar)

in the bar
the func run time is: 3.000192880630493

可以看出不修改bar()的源代码下，为其增加功能

最后看第三个例子：

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

def test1(func):    print(func)    return func

print(test1(bar))test1(bar)()

bar  = test1(bar)bar()

<function bar at 0x000002347ACE2E18>
<function bar at 0x000002347ACE2E18>
<function bar at 0x000002347ACE2E18>
in the bar
<function bar at 0x000002347ACE2E18>
in the bar

2.匿名函数：

lambda x:x*3

calc = lambda x:x*3

calc(3)

3.引用计数

python通过引用计数，回收内存

4.嵌套函数

在一个函数体内def另外一个函数

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

5.装饰器本质是函数，装饰其它函数,为其他函数添加附加功能。语法糖。

1.不能修改被装饰的函数的源代码

2.不能修改被装饰的函数的调用方式

成为透明性

实现：

1函数即“变量”,先定义再使用

2.高级函数

3.嵌套函数

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

return deco

def test1():    time.sleep(3)    print("in teh tes1")

def test2():    time.sleep(3)    print("in teh tes2")

test1=timer(test1)test1()

in teh tes1
the func run time is: 3.0001118183135986

最终为：

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

return deco@timer #test1=timer(test1)

def test1():    time.sleep(3)    print("in teh tes1")@timerdef test2():    time.sleep(3)    print("in teh tes2")

test1()

最最终为：import time

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

return deco@timerdef test1():    time.sleep(3)    print("in the test1")@timerdef test2(name,age):    time.sleep(3)    print("in the test",name,age)

test1()test2("roger",22)

补充：

username,password = "roger","abc123"

def auth(func):    def wrapper(*args,**kvargs):        username = input("Username:")        password = input("Password:")        if username == "roger" and password =="abc123":            print("User has passed authenticated")            func(*args,**kvargs)        else:            print("invalid username or password")            exit()    return wrapperdef index():    print("welcome to index page")

@authdef home():    print("welcome to home page")@authdef bbs():    print("welcome to bbs page")

index()home()bbs()

继续：

username,password = "roger","abc123"def auth(func):    def wrapper(*args,**kvargs):        username = input("Username:")        password = input("Password:")        if username == "roger" and password =="abc123":            print("User has passed authenticated")            resu = func(*args,**kvargs)            print("after authentication")            return resu        else:            print("invalid username or password")            exit()    return wrapperdef index():    print("welcome to index page")

@authdef home():    print("welcome to home page")    return "from home"@authdef bbs():    print("welcome to bbs page")

index()print(home())bbs()

再继续：

username,password = "roger","abc123"def auth(auth_type):    print("auth function args",auth_type)    def out_wrapper(func):        def wrapper(*args, **kvargs):            print("wrapper function args:", *args,*kvargs)            if auth_type == "local":                username = input("Username:")                password = input("Password:")                if username == "roger" and password == "abc123":                    print("User has passed authenticated")                    resu = func(*args, **kvargs)                    print("after authentication")                    return resu                else:                    print("invalid username or password")                    exit()            elif auth_type == "ldap":                print("执行ldap的验证")        return wrapper    return out_wrapperdef index():    print("welcome to index page")

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

index()print(home())bbs()

原文地址：https://www.cnblogs.com/wherewhenwho/p/9031195.html