On Sun, Dec 2, 2018 at 1:20 PM Chris Angelico <ros...@gmail.com> wrote:
> On Sun, Dec 2, 2018 at 11:08 PM Morten W. Petersen <morp...@gmail.com> > wrote: > > > > On Sun, Dec 2, 2018 at 12:49 PM Chris Angelico <ros...@gmail.com> wrote: > >> To my knowledge, len(x) == len(list(x)) for any core data type that > >> has a length. > > > > >>> len(range(0,100,3)) > > 34 > > >>> range(0,100,3).__len__ > > <method-wrapper '__len__' of range object at 0x7f144d5e3210> > > >>> range(0,100,3).__len__() > > 34 > > >>> > > > > But again, I guess an integer-to-be-calculated would be suitable > > for iterators where it is very expensive to do a list or other > > similar calculation. > > > > These operations take quite a bit of time: > > > > >>> x=list(range(0,100000000,3)) > > >>> y=len(list(range(0,100000000,3))) > > >>> > > > > Of course they take a lot of time - you're asking for the generation > of some thirty-three million integer objects, each one individually > built and refcounted (in CPython), just so you can count them. But my > point about the equivalency is that, rather than calculating > len(list(range(...))), you can calculate len(range(...)), and you can > be confident that you WILL get the same result. > Mm, yes, I was aware that it took up references, one more zero and it would dump a MemoryError. I hacked a bit of code today, got get my head around the concept of integer-of-unknown-size, and ended up with this so far: https://github.com/morphex/misc/blob/98e44915ffeb1cc3ec3050135ea503eb901c01e2/iterator.py I guess there could be of some (contrived?) use to have an iterator that will take different fractions, which will stop iterating over digits once a repeating pattern has been found. Anyway, the more I meddled with the idea of an integer-of-unknown-size, the more I think that it isn't necessary with the right use of other concepts and abstractions. It could however be a smaller part of a nice, clean pattern/concept. -Morten -- Videos at https://www.youtube.com/user/TheBlogologue Twittering at http://twitter.com/blogologue Blogging at http://blogologue.com Playing music at https://soundcloud.com/morten-w-petersen Also playing music and podcasting here: http://www.mixcloud.com/morten-w-petersen/ On Google+ here https://plus.google.com/107781930037068750156 On Instagram at https://instagram.com/morphexx/ -- https://mail.python.org/mailman/listinfo/python-list
