Hello everyone, I am Pablo from Argentina! This is my first email here, so just let me know if I am missing anything that is of use in this list, such as presenting myself. As for this topic in particular:
Although I might use it a lot (more than I would like to admit), I don't like this feature. First of all, I think it favors not-very-pretty code, effectively reducing the cost you pay for writing too-many-argument functions. It'd also obfuscate the code, and here I would like to quote the Zen of Python "explicit is better than implicit". It looks kind of similar (I know it has nothing to do in practice, but I think in mindset) to creating a dictionary of parameters that you pass to the function in order to avoid writing multiple args. If you are thinking of doing that, maybe the problem is that you are using a wrong design, and a programming language should "punish" it somehow. On Wed, May 6, 2020 at 6:55 PM Lewis Ball <lrjb...@gmail.com> wrote: > Joao S. O. Bueno wrote: > > Here - with the current inspect.Signature, it is straightforward > > to get a decorator that can do that covering most, if not all, > > corner cases, and even adding some extra functionality: > > https://gist.github.com/jsbueno/f689a181d50384f627b43b9b2aabe4f2 > > > > from inspect import signature, Parameter > > from functools import wraps, partial > > > > def autoassign(func=None, *, expand_kwargs=False): > > > > if not func: > > return partial(autoassign, expand_kwargs=expand_kwargs) > > sig = signature(func) > > @wraps(func) > > def wrapper(*args, **kwargs): > > instance = args[0] > > bound_args = sig.bind(*args, **kwargs) > > bound_args.apply_defaults() > > for i, (key, value) in enumerate(bound_args.arguments.items()): > > if i == 0 or sig.parameters[key].kind == > Parameter.POSITIONAL_ONLY: > > continue > > if expand_kwargs and sig.parameters[key].kind == > > Parameter.VAR_KEYWORD: > > for kwkey, kwvalue in value.items(): > > setattr(instance, kwkey, kwvalue) > > continue > > setattr(instance, key, value) > > return func(*args, **kwargs) > > return wrapper > > > > """ > > class A: > > @autoassign > > def __init__(self, a, b, c=3): > > pass > > > > a = A(1, 2) > > assert a.a == 1 and a.b == 2 and a.c == 3 > > """ > > Is there a good reason to exclude positional only args from this? I > imagine if you are passing them to init you still want them to be treated > internally in the same way as the other args. > > > Could we put this into the standard library, so that IDEs and linters are > > programmed to recognise it? > > I agree, without this being recognised by linters/IDEs any attrs will show > with ugly warnings which would stop anyone from using it. > _______________________________________________ > Python-ideas mailing list -- python-ideas@python.org > To unsubscribe send an email to python-ideas-le...@python.org > https://mail.python.org/mailman3/lists/python-ideas.python.org/ > Message archived at > https://mail.python.org/archives/list/python-ideas@python.org/message/IMBONGILTSVKQ6JXYU3PEEN5XY4ICD5K/ > Code of Conduct: http://python.org/psf/codeofconduct/ >
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