On Thu, Oct 4, 2018 at 10:58 AM Steven D'Aprano <st...@pearwood.info> wrote:
> While keyword arguments have to be identifiers, using **kwargs allows > arbitrary strings which aren't identifiers: > > py> def spam(**kwargs): > ... print(kwargs) > ... > py> spam(**{"something arbitrary": 1, '\n': 2}) > {'something arbitrary': 1, '\n': 2} > > > There is some discussion on Python-Ideas on whether or not that > behaviour ought to be considered a language feature, an accident of > implementation, or a bug. > > I would expect this to be costly/annoying for implementations to enforce, doing it at call time is probably too late to be efficient, it would need help from dicts themselves or even strings. A hack that currently works because of this is with dict itself: >>> d = {'a-1': 1, 'a-2': 2, 'a-3': 3} >>> d1 = dict(d, **{'a-2': -2, 'a-1': -1}) >>> d1 is d False >>> d1 {'a-1': -1, 'a-2': -2, 'a-3': 3} >>>
_______________________________________________ Python-Dev mailing list Python-Dev@python.org https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com