装饰器

一个完整的decorator的写法如下：

import functools

def log(func):
    @functools.wraps(func)
    def wrapper(*args, **kw):
        print('call %s():' % func.__name__)
        return func(*args, **kw)
    return wrapper

@log    ## now = log(now)
def now():
    print('2015-3-25')

>>> now()
call now():
2015-3-25

或者针对带参数的decorator：

import functools

def log(text):
    def decorator(func):
        @functools.wraps(func)
        def wrapper(*args, **kw):
            print('%s %s():' % (text, func.__name__))
            return func(*args, **kw)
        return wrapper
    return decorator

@log('execute')    ## now = log('execute')(now)
def now():
    print('2015-3-25')

>>> now()
execute now():
2015-3-25