python 装饰器

def logging(level):
    def wrapper(func):
        def inner_wrapper(*args, **kwargs):
            print "[{level}]: enter function {func}()".format(
                level=level,
                func=func.__name__)
            return func(*args, **kwargs)
        return inner_wrapper
    return wrapper

@logging(level='INFO')
def say(something):
    print "say {}!".format(something)

# 如果没有使用@语法，等同于
# say = logging(level='INFO')(say)

@logging(level='DEBUG')
def do(something):
    print "do {}...".format(something)

if __name__ == '__main__':
    say('hello')
    do("my work")

装饰器调用顺序

#!/usr/bin/env python
# encoding: utf-8

def decorator_a(func):
    print func
    print 'Get in decorator_a'
    def inner_a(*args, **kwargs):
        print 'Get in inner_a'
        return func(*args, **kwargs)
    return inner_a

def decorator_b(func):
    print func
    print 'Get in decorator_b'
    def inner_b(*args, **kwargs):
        print 'Get in inner_b'
        return func(*args, **kwargs)
    return inner_b

@decorator_b
@decorator_a
def f(x):
    print 'Get in f'
    return x * 2

f(1)

执行结果

<function f at 0x100d4b6e0>
Get in decorator_a
<function inner_a at 0x100d4bde8>
Get in decorator_b
Get in inner_b
Get in inner_a
Get in f

f(1)等价于decorator_b(decorator_a(f))(1)