python 装饰器

from functools import wraps


def print_task(fn, *args, **kwargs):
    def _decorate(fn, *args, **kwargs):
        @wraps(fn)
        def wrapper(*args, **kwargs):
            print args[0]
            out = apply(fn, args, kwargs)
            return out
        return wrapper
    print fn.__name__
    if fn:
        return _decorate(fn)
    return _decorate

@print_task
def a(x):
    print "i am a"
    print x


a("sads")


--------------------------------------------------out:
a
sads
i am a
sads