On Mon, Feb 25, 2013 at 12:41 AM, Andrew Robinson <andr...@r3dsolutions.com> wrote: >> Intuitively, it should result in an infinite loop starting at 0. But >> ranges require a stop value for a very good reason -- it should not be >> this easy to accidentally create an infinite for loop. > > ... > and, besides, the same is true with other constructions of loops.... > > while a: # Damn easy, if a is accidentally true!
Notice I specifically said an "infinite *for* loop". While loops are meant to be indeterminate in the number of iterations they will take going into the loop; for loops are not. >> The next problem you run into is that the semantics of negative >> numbers are completely different between slices and ranges. Consider >> this code: >> >> s = (-5:6) >> for i in s: >> print(i) >> for i in range(6)[s]: >> print(i) > > I don't find this difference to be necessary, nor objectionable. > > It is less inconsistent, in my view, to allow that > ([ 1,2,3,4,5 ])[-1:2] produce [5,1,2] than an empty list; > and ([ 1,2,3,4,5])[2:-1] does produce an empty list. > > I have been looking for actual programs that this would break for over two > months now, and I haven't been finding any. I am willing to run any > mainstream application you can find on test-patched python! Yes, I recollect now that we have already had this discussion. -- http://mail.python.org/mailman/listinfo/python-list
