On Tue, Jun 30, 2020 at 11:55 AM Rhodri James <rho...@kynesim.co.uk> wrote:
> On 30/06/2020 18:31, Christopher Barker wrote: > > The first improvement on that was the iter* methods, and then (inspired > by > > JAVA) it was determined that we could have view objects that could > provide > > efficient iterators, and also set-like behavior. But I don't see any > > comments in the PEP about why indexing was rejected, but it's implicit in > > the fact that dicts were explicitly unordered at the time that PEP was > > written. > > I'm sorry, I don't think that logic holds water. Dicts at the time were > explicitly unordered (and I still mostly find it more useful to think of > them as unordered), but iterators are explicitly ordered. You probably > couldn't rely on that order being consistent if you fiddled with the > dict between iterations, but that's not behaviour we encourage with > list-handling either. > > Don't get me wrong, if it's not going to cause performance issues I > think being able to index views would be great, but I don't think this > is the right way to justify it. > I wasn't justifying it -- I was simply saying that no one ever specifically decided that we DIDN'T want to be able to index dict views -- when they were created, it simply wasn't an option. Now it is, so we need to rethink it. > if it's not going to cause performance issues I can't see how it could possibly *cause* performance issues. It isn't as great performance as we would like, but I think it's still as good, and probably much better, than any other way to accomplish the same thing. Even if the performance were bad, I don't think we'd be handing out a foot gun here: who's going to write: my_dict.items[n] when they know what the key is for the nth item? Other than the usual "more code to write and maintain", I still don't see a downside. -CHB > If anyone who knows could comment on the feasibility, that would be > great too :-) > > -- > Rhodri James *-* Kynesim Ltd > _______________________________________________ > 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/5ZZ2MNP3YEJDXBCSJVTPJN4KTA64HKAO/ > Code of Conduct: http://python.org/psf/codeofconduct/ > -- Christopher Barker, PhD Python Language Consulting - Teaching - Scientific Software Development - Desktop GUI and Web Development - wxPython, numpy, scipy, Cython
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