On Sun, Dec 8, 2019 at 9:27 PM Andrew Barnert <abarn...@yahoo.com> wrote:
> On Dec 8, 2019, at 20:59, Guido van Rossum <gu...@python.org> wrote: > > > > But even if you know about 2-arg next(), the next(iter(it), default) > version is not quite trivial to come up with -- you have to remember to put > the iter() call in -- but IMO the main problem is that not enough people > know about 2-arg next(), and that makes it pass the second bar. > > Are people who never find 2-arg next going to find itertools.first? > Nobody is going to write a blog post about 2-arg next() (there just isn't enough for more than a sentence or two) but people write tutorials about itertools all the time, since it's such a rich module. So I think it's likely that first() will get some exposure that way. > I think most people who use itertools regularly enough to look there are > people who already know 2-arg next (and also, mostly people who are > “thinking functionally”, for that matter). Other people will discover it if > someone points them there on -list or on StackOverflow or as student help > or whatever, but they can already discover 2-arg next the same ways. In > fact, what they’re probably going to find on StackOverflow is an answer all > about 2-arg next, with a little edited-in footnote or comment saying “if > you’re using the upcoming 3.9, you can use first instead of next and leave > out the call to iter”. > If the only argument against adding a new feature is that existing documentation doesn't yet describe it, I'm not too concerned. :-) I do have to admit that I'm probably biased because I didn't recall 2-arg next() myself until it was mentioned in this thread. But I doubt that I'm alone -- I've seen plenty of code written by people (other than me :-) who clearly didn't know about it either. I can't show examples, since what I recall was in a large proprietary code base to which I no longer have access. I did find this, in test_itertools.py no less: >>> def pairwise(iterable): ... "s -> (s0,s1), (s1,s2), (s2, s3), ..." ... a, b = tee(iterable) ... try: ... next(b) ... except StopIteration: ... pass ... return zip(a, b) Methinks that could have been three lines shorter using next(b, None). -- --Guido van Rossum (python.org/~guido) *Pronouns: he/him **(why is my pronoun here?)* <http://feministing.com/2015/02/03/how-using-they-as-a-singular-pronoun-can-change-the-world/>
_______________________________________________ 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/TTA4RV2MBLYURZQSXT6RZLFGXO3A73KL/ Code of Conduct: http://python.org/psf/codeofconduct/
