On Wed, Nov 22, 2017 at 8:48 PM, Sven R. Kunze <srku...@mail.de> wrote:
> Isn't yield like a return? > Enough like it to make a good case, I'd say. > A return in a list/dict/set comprehension makes no sense to me. > Nor me, nor the vast majority of instance. But nowadays yield is more of a synchronisation point. If something is valid syntax we should presumably like to have defined semantics. > So, +1 on SyntaxError from me too. > I'd tend to agree. This would give more time to discuss the intended semantics: giving it meaning later might be a more cautious approach that would allow decisions to be made in the light of further experience. I would urge developers, in their improvements to the language to support asynchronous programming, to bear in mind that this is (currently) a minority use case. Why the rush to set complex semantics in stone? > regards Steve > Cheers. > > On 22.11.2017 21:29, David Mertz wrote: > > Inasmuch as I get to opine, I'm +1 on SyntaxError. There is no behavior > for that spelling that I would find intuitive or easy to explain to > students. And as far as I can tell, the ONLY time anything has ever been > spelled that way is in comments saying "look at this weird edge case > behavior in Python." > > On Nov 22, 2017 10:57 AM, "Jelle Zijlstra" <jelle.zijls...@gmail.com> > wrote: > > > > 2017-11-22 9:58 GMT-08:00 Guido van Rossum <gu...@python.org>: > >> Wow, 44 messages in 4 hours. That must be some kind of record. >> >> If/when there's an action item, can someone summarize for me? >> >> The main disagreement seems to be about what this code should do: > > g = [(yield i) for i in range(3)] > > Currently, this makes `g` into a generator, not a list. Everybody seems to > agree this is nonintuitive and should be changed. > > One proposal is to make it so `g` gets assigned a list, and the `yield` > happens in the enclosing scope (so the enclosing function would have to be > a generator). This was the way things worked in Python 2, I believe. > > Another proposal is to make this code a syntax error, because it's > confusing either way. (For what it's worth, that would be my preference.) > > There is related discussion about the semantics of list comprehensions > versus calling list() on a generator expression, and of async semantics, > but I don't think there's any clear point of action there. > > >> -- >> --Guido van Rossum (python.org/~guido <http://python.org/%7Eguido>) >> >> _______________________________________________ >> 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/jelle.zij >> lstra%40gmail.com >> >> > > _______________________________________________ > 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/mertz% > 40gnosis.cx > > > > > _______________________________________________ > Python-Dev mailing > listPython-Dev@python.orghttps://mail.python.org/mailman/listinfo/python-dev > > Unsubscribe: > https://mail.python.org/mailman/options/python-dev/srkunze%40mail.de > > > > _______________________________________________ > 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/ > steve%40holdenweb.com > >
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