python之装饰器

高阶函数：

def func():
    print("This is func")


def foo(func):
    print("this is foo")
    func()
    return func


foo(func)    # 将函数 func 作为参数传递给 foo
print(foo(func))    # foo 的返回值是


执行结果：
this is foo
This is func
this is foo
This is func
<function func at 0x000001B6D6A02EA0>

匿名函数：

def foo():
    print("this is ", foo)


print(foo)    # 表示的是函数
foo()    # 执行foo函数

foo = lambda x : x * 2   # 匿名函数
print(foo("10"))    # 执行的是 lambda 表达式，而不是原来的 foo 函数，因为 foo 被重新定义了


执行结果：

<function foo at 0x000002D11FF4AB70>
this is foo
1010

 装饰器：

import time

username = "guoxf"
password = "123456"

def auth(a):
    print("ahth a:", a)
    def first(func):
        print("first func:", func)
        def second(*args, **kwargs):
            start_time = time.time()
            print(*args, **kwargs)
            user = input("Username:")
            pwd = input("Password:")
            if user == username and pwd == password:
                func(*args, **kwargs)
                stop_time = time.time()
                print("run time:%s" % (stop_time - start_time))
            else:
                exit("输入错误，退出程序。。。")

        return second
    print("this is first", first)

    return first


def test1():
    print("welcome to chaina...")


# @auth("local")     
def test2(username, password):
    time.sleep(1)
    print("this is test2...")


@auth("authtication")
def test3():
    time.sleep(1.5)
    print("what are you doing...")



first1 = auth("local")    # first1 指向 auth 函数的返回值first 的函数
test2=  first1(test2)    # test2 指向 first 函数的返回值second 的函数； test2 传给了 func
test2("guoxf","123456")    # 执行second 函数

test3()

执行结果：

ahth a: authtication
this is first <function auth.<locals>.first at 0x000002093E80AF28>
first func: <function test3 at 0x000002093E82F048>
ahth a: local
this is first <function auth.<locals>.first at 0x000002093E80AF28>
first func: <function test2 at 0x000002093E80AEA0>
guoxf 123456
Username:guoxf
Password:123456
this is test2...
run time:140.81427788734436

Username:guoxf
Password:1234567
输入错误，退出程序。。。

下图中红框圈中的部分，两者结果相同