> On Oct 6, 2021, at 10:53 AM, Finn Mason <finnjavie...@gmail.com> wrote: > > > I'm not a huge fan. Sure, dicts are ordered now, but I doubt that many people > use that feature. I honestly still think of them as unordered ;) > There’s tons of code that relies on dicts being ordered. Some just don’t know it. For example, dataclasses relies on ordered dicts.
I think we can rely on dicts being ordered as a language guarantee for the rest of time. Eric > Let's talk code clarity. After all, to quote GvR, "Code is more often read > than written." (I may have gotten the wording wrong, I just wrote it off the > top of my head.) To me, the presence of a dict suggests that order doesn't > matter. If you want order, communicate that by using > `collections.OrderedDict`, a fully-featured dict subclass where the point is > the order! You can get the first or last key/item pairs with `.popitem()`. It > works! > > OrderedDict documentation: > https://docs.python.org/3.10/library/collections.html#collections.OrderedDict > > We could add indexing to OrderedDict, which would return key/value pairs. > (While we're talking about collections, why don't we return a namedtuple ;) ) > As for adding functions to `itertools`, sure, I'm for it. We don't need > people writing `next(iter(iterable))` just to get the first item. > > > -- > Finn > >> On Wed, Oct 6, 2021, 8:02 AM Steven D'Aprano <st...@pearwood.info> wrote: >> On Wed, Oct 06, 2021 at 11:11:09AM +0100, Alex Waygood wrote: >> > > The temptation to insist "see, YAGNI!" at this point I shall resist. >> > >> > *You* might not need it, but I've seen it come up a lot on Stack >> > Overflow, and all too often people end up going for the much less >> > efficient solution. I personally have also written code with practical >> > applications using `next(iter(mydict))`. >> >> Under what circumstances do you care what the first key in a dict is, >> without going on to care about the second, third, fourth etc? >> >> They are surely extremely niche, or artificial, or both, e.g. the >> Stackoverflow problem you link to: "find the first non-repeating >> character in a string -- using only one loop". Why the *first* rather >> than any, or all? >> >> In any case, the presence of one or two uses for a piece of >> functionality doesn't mandate that we make this a builtin. Your solution >> with next() is perfectly adequate. >> >> The other suggested methods are even more obscure. Why have a method >> for returning the first value, without knowing the key? >> >> "I don't know what the first key is, and I don't care, but I know that >> whatever it is, it maps to the value 17." >> >> Now what are you going to do with that knowledge? This seems like a >> method in desperate need of a use-case. >> >> >> [...] >> > I agree that it's a lot of methods to add. That's precisely why I >> > prefer Inada Naoki's suggestion of additions to itertools >> >> Whether they are added to dict or itertools, there are still nine of >> them, and they are pretty much near clones of each other: >> >> # first_ and last_ whatsits >> next([iter|reversed](obj.[keys|values|items]())) >> >> if you will excuse the misuse of hybrid Python/BNF syntax :-) >> >> >> >> -- >> Steve >> _______________________________________________ >> 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/T3TOFAFBPGY44LOVKSMVZJGBNQ7MUNEL/ >> Code of Conduct: http://python.org/psf/codeofconduct/ > _______________________________________________ > 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/3RKWSNOO4J7WJWBYFXMA7HKPBVZVIF3S/ > Code of Conduct: http://python.org/psf/codeofconduct/
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