python局部变量高级函数匿名函数嵌套函数装饰器

Posted 2020-11-04 wherewhenwho

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 time
def 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 time
def 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")
@timer
def 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
@timer
def test1():
    time.sleep(3)
    print("in the test1")
@timer
def 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 wrapper
def index():
    print("welcome to index page")

@auth
def home():
    print("welcome to home page")
@auth
def 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 wrapper
def index():
    print("welcome to index page")

@auth
def home():
    print("welcome to home page")
    return "from home"
@auth
def 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_wrapper
def 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()