python 装饰器

def works_for_all(func):
    def inner(*args, **kwargs):
        print("I can decorate any function")
        return func(*args, **kwargs)
    return inner

例子一

def make_pretty(func):
    def inner():
        print("I got decorated")
        func()
    return inner

def ordinary():
    print("I am ordinary")

执行

>>> ordinary()
I am ordinary

>>> # let's decorate this ordinary function
>>> pretty = make_pretty(ordinary)
>>> pretty()
I got decorated
I am ordinary

例子二

def make_pretty(func):
    def inner():
        print("I got decorated")
        func()
    return inner

@make_pretty
def ordinary():
    print("I am ordinary")

ordinary()

输出

I got decorated
I am ordinary

例子三

def star(func):
    def inner(*args, **kwargs):
        print("*" * 30)
        func(*args, **kwargs)
        print("*" * 30)
    return inner

def percent(func):
    def inner(*args, **kwargs):
        print("%" * 30)
        func(*args, **kwargs)
        print("%" * 30)
    return inner

@star
@percent
def printer(msg):
    print(msg)
printer("Hello")

输出

******************************
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
Hello
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
******************************

上面的

@star
@percent
def printer(msg):
    print(msg)

相当于

def printer(msg):
    print(msg)
printer = star(percent(printer))