On 23 November 2017 at 13:04, Ivan Levkivskyi <levkivs...@gmail.com> wrote: > Let us forget for a moment about other problems and focus on this one: list > comprehension is currently not equivalent to a for-loop. > There are two options: > - Fix this, i.e. make comprehension equivalent to a for-loop even in edge > cases (Serhiy seems ready to do this) > - Prohibit all cases when they are not equivalent > > I still prefer option one. But I see your point, option two is also an > acceptable fix. > Note that there were not so many situations when some code became > SyntaxError later. > I don't see why this particular case qualifies for such a radical measure as > an exception to syntactic rules, > instead of just fixing it (sorry Nick :-)
My main concern is that comprehension is not equivalent to a for loop for a specific reason - the scope issue. Has anyone looked back at the original discussions to confirm *why* a function was used? My recollection: >>> i = 1 >>> a = [i for i in (1,2,3)] >>> print(i) 1 Serihy's approach (and your described expansion) would have print(i) return NameError. So - do we actually have a proposal to avoid the implied function that *doesn't* break this example? I'm pretty sure this was a real-life issue at the time we switched to the current implementation. Paul _______________________________________________ Python-Dev mailing list Python-Dev@python.org https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
