[Python-ideas] Syntax for allowing extra keys when unpacking a dict as keyword arguments

[Viktor Roytman]

That is an interesting solution. In the case of a function from another 
library, you could apply the decorator as needed like.

    fief(func)(**{'a': 1, 'b': 2})

It looks a little strange, but I've seen stranger.

On Friday, April 12, 2019 at 12:18:34 PM UTC-4, Lucas Bourneuf wrote:
>
> Hello ! 
>
> I made *fief*, a small python package allowing just that using a 
> decorator: 
>
>     from fief import filter_effective_parameters as fief 
>
>     @fief 
>     def func(a, b): 
>         # some implementation 
>
>     # and then, use it as you want to: 
>     func(**MY_BIG_CONFIG_DICT_WITH_MANY_WEIRD_KEYS) 
>
> The code is quite simple. You may want to use it, with modifications (i 
> didn't touch the code for months, maybe years ; it could probably be 
> improved now). 
> Link: https://github.com/aluriak/fief 
>
> The code: 
>
> def filter_effective_parameters(func): 
>     """Decorator that filter out parameters in kwargs that are not related 
> to 
>     any formal parameter of the given function. 
>     """ 
>     @wraps(func) 
>     def wrapper(*args, **kwargs): 
>         formal_parameters = frozenset(signature(func).parameters.keys()) 
>         return func(*args, **{ 
>             arg: value 
>             for arg, value in kwargs.items() 
>             if arg in formal_parameters 
>         }) 
>     return wrapper 
>
> Best regards, 
> --lucas 
>
>
>
> ----- Mail original ----- 
> > De: "Viktor Roytman" <viktor... at gmail.com <javascript:>> 
> > À: "python-ideas" <python... at googlegroups.com <javascript:>> 
> > Envoyé: Vendredi 12 Avril 2019 18:01:43 
> > Objet: Re: [Python-ideas] Syntax for allowing extra keys when unpacking 
> a dict as keyword arguments 
>
> > I could see this being an option, but to someone unfamiliar with it, it 
> > might seem strange that * unpacks iterables, ** unpacks dicts, and *** 
> is a 
> > special thing only for keyword arguments that mostly behaves like **. 
> > 
> > On Friday, April 12, 2019 at 11:26:37 AM UTC-4, Bruce Leban wrote: 
> >> 
> >> 
> >> On Fri, Apr 12, 2019, 8:12 AM Viktor Roytman <viktor... at gmail.com 
> >> <javascript:> wrote: 
> >> 
> >>> 
> >>>     >>> func(**{'a': 1, 'b': 2}) 
> >>>     Traceback (most recent call last): 
> >>>       File "<stdin>", line 1, in <module> 
> >>>     TypeError: func() got an unexpected keyword argument 'b' 
> >>> 
> >> 
> >> Perhaps func(***kws)? 
> >> 
> >> I think this is a real problem given the frequent convention that you 
> can 
> >> freely add fields to json objects with the additional fields to be 
> ignored. 
> >> 
> > 
> > _______________________________________________ 
> > Python-ideas mailing list 
> > Python... at python.org <javascript:> 
> > https://mail.python.org/mailman/listinfo/python-ideas 
> > Code of Conduct: http://python.org/psf/codeofconduct/ 
> _______________________________________________ 
> Python-ideas mailing list 
> Python... at python.org <javascript:> 
> https://mail.python.org/mailman/listinfo/python-ideas 
> Code of Conduct: http://python.org/psf/codeofconduct/ 
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.python.org/pipermail/python-ideas/attachments/20190412/52afc0b4/attachment-0001.html>