带参数的装饰器-python

先来看看一般的情况

def use_logging(func):
    def wrapper(*args, **kwargs):
        if level == 'warn':
            logging.warn('%s is running' % func.__name__)
        return func(*args)
    return wrapper

@use_logging
def foo(name = 'foo'):
    print ('i am %s' % name)

foo()

@use_logging 相当于
foo = use_logging(foo), foo 指向了 return 的wrapper，
foo()相当于 wrapper()，直接运行了wrapper里的内容以及func(*args)即def foo(name = ‘foo’)里的内容。
理解了基本的，来看看带参数的装饰器

import logging
def use_logging(level):
    def decorator(func):
        def wrapper(*args, **kwargs):
            if level == 'warn':
                logging.warn('%s is running' % func.__name__)
            return func(*args)
        return wrapper
    return decorator

@use_logging(level = 'warn')
def foo(name = 'foo'):
    print ('i am %s' % name)

foo()

@use_logging(level = ‘warn’)相当于 use_logging(level = ‘warn’)(foo)就相当于返回的decorator(foo)，即foo = decorator(foo)，其余思路与上相同。