Path: csiph.com!fu-berlin.de!uni-berlin.de!not-for-mail
From: Ian Kelly <ian.g.kelly@gmail.com>
Newsgroups: comp.lang.python
Subject: Re: Meta decorator with parameters, defined in explicit functions
Date: Fri, 1 Jul 2016 23:09:10 -0600
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Message-ID: <mailman.15.1467436194.2295.python-list@python.org>
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On Fri, Jul 1, 2016 at 4:08 PM, Lawrence D=E2=80=99Oliveiro
<lawrencedo99@gmail.com> wrote:
> On Tuesday, June 28, 2016 at 5:03:08 PM UTC+12, Ben Finney wrote:
>> There is a clever one-line decorator that has been copy-pasted without
>> explanation in many code bases for many years::
>>
>>     decorator_with_args =3D lambda decorator: lambda *args, **kwargs: la=
mbda func: decorator(func, *args, **kwargs)
>>
>
> For those who want docstrings, I=E2=80=99ll give you docstrings:
>
>     def decorator_with_args(decorator) :
>         "given function decorator(func, *args, **kwargs), returns a decor=
ator which," \
>         " given func, returns the result of decorator(func, *args, **kwar=
gs)."
>
>         def decorate(*args, **kwargs) :
>
>             def generated_decorator(func) :
>                 return \
>                     decorator(func, *args, **kwargs)
>             #end generated_decorator
>
>         #begin decorate
>             generated_decorator.__name__ =3D "decorator_{}".format(decora=
tor.__name__)
>             generated_decorator.__doc__ =3D "decorator which applies {} t=
o the previously-specified arguments".format(decorator.__name__)
>             return \
>                 generated_decorator
>         #end decorate
>
>     #begin decorator_with_args
>         decorate.__name__ =3D "decorate_with_{}".format(decorator.__name_=
_)
>         decorate.__doc__ =3D "generates a decorator which applies {} to t=
he given arguments".format(decorator.__name__)

You should use functools.wraps instead of clobbering the decorated
function's name and docstring:

        @functools.wraps(decorator)
        def decorate(*args, **kwargs):
            ...

>         return \
>             decorate

Just to satisfy my own curiosity, do you have something against
putting the return keyword and the returned expression on the same
line?