On Wed, Nov 18, 2020 at 2:35 AM Joao S. O. Bueno <jsbu...@python.org.br> wrote: > Also, see it as potentially making a lot of code error-prone: > let's say one gets passed a generator where a sequence is expected. > In current Python, if an item is accessed by index, one just get an explicit > IndexError. If objects change to having indexes, two consecutive access > to `gen[1]` will consume the generator and return different values. That > could be very confusing.
Extremely confusing, and I think that would be enough to kill the idea. > On the other hand, as I said, I can't come up with > a simple pattern to get the nth item - so probably we > should think of an easy and performant way. The very concept of "the nth item" doesn't work with generators, so I think there's little reason to try to define it usefully. However... > One way I can think of is to have a named parameter > to the `next` built-in that would allow one to move forward more than one > position. > > Say: `fith_element = next(gen, skip=4) ` (Ohh, the strong fifth element - Boron?) > and finally, one way I could think of retrieving the n > element is: > > In [19]: a = (i for i in range(0, 100, 10)) > > In [20]: next(b for i, b in enumerate(a) if i==5) > Out[20]: 50 > > It definitely feels like there should be a simpler way, > but I just could not come up with it. ... there may be some value in this simple "skip" option. For the record, the most normal way to do this sort of thing would be the islice function: https://docs.python.org/3/library/itertools.html#itertools.islice but if all you want to do is "skip the next four, then take the next one after that", it would be convenient to quickly pump the generator a few times before returning a value. This isn't something I often need personally, but I can definitely see the value of it. +0.5; this does get asked for a good bit, and a keyword argument on next() would be a lot less confusing than directly subscripting a generator. ChrisA _______________________________________________ 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/5L2BIH2OZZTHIATKRDDKNLLJDPY5TACU/ Code of Conduct: http://python.org/psf/codeofconduct/
