On Sun, Aug 23, 2020 at 9:42 PM Todd <toddr...@gmail.com> wrote: > I think it is worth directly discussing the availability of slices in PEP > 472-style keyword indices, since we seem to have mostly converged on a > dunder method signature. This is an issue that has been alluded to > regarding keyword-based (labelled) indices but not directly addressed. The > basic syntax would be something like d[x=1:3]. >
As I mentioned in another thread, I think the syntax in which the initial argument of the slice is missing may be visually confusing, as it is too similar to the walrus operator. d[x=:3] or d[x=:] There's precedent for combinations of symbols that have different meanings when swapped. For example: x += 3 vs x =+ 3 However, the second case will be usually formatted as x = +3, as per PEP 8 <https://www.python.org/dev/peps/pep-0008/#other-recommendations> So unless PEP8 is updated to require/suggest spaces around a keyword index (which I'm not proposing), then I am -1 for the suggested feature, at least when the initial element is missing. > > I am strongly in favor of having slices. The main motivating factor for > me, labelled dimensions in xarray, would be much, much less useful without > support for slices. In fact, as PEP 472 currently mentions, the big > benefit of indexing over method calls is that indexing supports slice > syntax while method calls don't. > > In a more general sense, I feel not allowing slices would create an > artificial distinction between labelled and positional indices that I don't > think is justified. They would work the same, except for slices where > labelled indices behave differently. It would be a strange gotcha. > > So I think any revision to PEP 472 or new PEP should directly and > explicitly support the use of slices. > _______________________________________________ > 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/TOABKD7A5X653BTTU3MZICWURNGPMY47/ > Code of Conduct: http://python.org/psf/codeofconduct/ > -- Sebastian Kreft
_______________________________________________ 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/IQJNOQS2LKHWSSYAJX7KDNWJ5ZFZ25N4/ Code of Conduct: http://python.org/psf/codeofconduct/
