On Sat, Mar 3, 2018 at 7:04 AM, Eric Fahlgren <ericfahlg...@gmail.com> wrote: > > On Fri, Mar 2, 2018 at 10:27 AM, Jelle Zijlstra <jelle.zijls...@gmail.com> > wrote: >> >> >> I wonder if we could have a more limited change to the language that would >> allow only the as/while use cases. Specifically, that means we could do: >> >> while do_something() as x: >> print(x) > > > The "while" case is the only part of the PEP that has any traction with me. > It doesn't add any keywords, scope can be identical to "with" and it cleans > up a code pattern that is very common.
How often do you have a loop like this where you actually want to capture the exact condition? I can think of two: regular expressions (match object or None), and socket read (returns empty string on EOF). This simplified form is ONLY of value in that sort of situation; as soon as you want to add a condition around it, this stops working (you can't say "while do_something() is not _sentinel as x:" because all you'll get is True). And if you are looking for one specific return value as your termination signal, you can write "for x in iter(do_something, None):". > Every one of these comprehension examples has me scratching my head, > thinking back a couple hundred (thousand? :) ) posts to Barry's quip, > "Sometimes a for loop is just better" (or something along those lines). True, but there's a code smell to an unrolled 'for' loop that could have been a comprehension had it not been for one trivial point of pedantry. So there are advantages and disadvantages to each. ChrisA _______________________________________________ Python-ideas mailing list Python-ideas@python.org https://mail.python.org/mailman/listinfo/python-ideas Code of Conduct: http://python.org/psf/codeofconduct/
