Python-ideas

Download

python-ideas@python.org

July 2013

85 participants
51 discussions

Re: [Python-ideas] "Iteration stopping" syntax [Was: Is this PEP-able? for X in ListY while conditionZ:]
by Shane Green July 1, 2013

July 1, 2013

Yes, but it only works for generator expressions and not comprehensions. My opinion of that workaround is that it’s also a step backward in terms of readability. I suspect if i < 50 else stop() would probably also work, since it throws an exception. That’s better, IMHO. On Jun 28, 2013, at 6:38 PM, Andrew Carter <acarter(a)g.hmc.edu> wrote: > Digging through the archives (with a quick google search) http://mail.python.org/pipermail/python-ideas/2013-January/019051.html, if you really want an expression it seems you can just do > > def stop(): > raise StopIteration > list(i for i in range(100) if i < 50 or stop()) > > it seems to me that this would provide syntax that doesn't require lambdas. > > > > > > > On Fri, Jun 28, 2013 at 4:50 PM, Alexander Belopolsky <alexander.belopolsky(a)gmail.com> wrote: > > > > On Fri, Jun 28, 2013 at 7:38 PM, Shane Green <shane(a)umbrellacode.com> wrote: > .. > [x until condition for x in l ...] or > [x for x in l until condition] > > Just to throw in one more variation: > > [expr for item in iterable break if condition] > > (inversion of "if" and "break"reinforces the idea that we are dealing with an expression rather than a statement - compare with "a if cond else b") > > _______________________________________________ > Python-ideas mailing list > Python-ideas(a)python.org > http://mail.python.org/mailman/listinfo/python-ideas

8 21