On Dec 9, 2019, at 22:07, Wes Turner <wes.tur...@gmail.com> wrote: > > > Sets are not collections.abc.Sequence because they do not implement > __getitem__. > Are there other unordered Iterables in the standard library
Again, it depends on what you’re trying to distinguish by that word “unordered”. Mappings (including dict) and their views, Sets (including frozenset), Iterators (including file objects, map, filter, generators, and most itertools functions), and many other things are Iterables without being Sequences. I have no idea which if any of these you mean by “unordered”. For every single one of them, just like for set, first(it) will give you the same value as list(it)[0] (albeit a different exception if they’re empty), so I don’t see why any of them are confusing. What else would you expect first to do? And, without knowing why you think first should mention any of them, I have no idea which ones it should mention. >> On Tue, Dec 10, 2019 at 12:44 AM Tim Peters <tim.pet...@gmail.com> wrote: >> >> ... as is my _current_ idiom: >> >> for a in iterable: >> break >> else: >> raise ... > > Is this pattern in the tutorial? No, but you will find it on StackOverflow. I don’t think it needs to be in the tutorial. If needing to raise a specific exception—or just not StopIteration—is common enough that novices need to learn it, I think it’s common enough that it should be given a name and put in the itertools recipes or module, or at least pointed out in more-itertools, rather than teaching people to spell it out every time. >> Plain old >> >> a = first(iterable) >> >> would be perfect - but only if it raised. > > +1. How is this distinct from: > > first = next Because first works with any Iterable; next works only with iterators. _______________________________________________ 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/Q7L5ML4MQRIKTFS2ZYX3N6TB2UL7MFEJ/ Code of Conduct: http://python.org/psf/codeofconduct/
