On 14 October 2017 at 17:50, Nick Coghlan <ncogh...@gmail.com> wrote: > On 14 October 2017 at 21:56, Paul Moore <p.f.mo...@gmail.com> wrote: > > TL;DR of below: PEP 550 currently gives you what you're after, so your > perspective counts as a preference for "please don't eagerly capture the > creation time context in generators or coroutines".
Thank you. That satisfies my concerns pretty well. > The suggestion has been made that we should instead be capturing the active > context when "url_get(url)" is called, and implicitly switching back to that > at the point where await is called. It doesn't seem like a good idea to me, > as it breaks the "top to bottom" mental model of code execution (since the > "await cr" expression would briefly switch the context back to the one that > was in effect on the "cr = url_get(url)" line without even a nested suite to > indicate that we may be adjusting the order of code execution). OK. Then I think that's a bad idea - and anyone proposing it probably needs to explain much more clearly why it might be a good idea to jump around in the timeline like that. > If you capture the context eagerly, then there are fewer opportunities to > get materially different values from "data = list(iterable)" and "data = > iter(context_capturing_iterable)". > > While that's a valid intent for folks to want to be able to express, I > personally think it would be more clearly requested via an expression like > "data = iter_in_context(iterable)" rather than having it be implicit in the > way generators work (especially since having eager context capture be > generator-only behaviour would create an odd discrepancy between generators > and other iterators like those in itertools). OK. I understand the point here - but I'm not sure I see the practical use case for iter_in_context. When would something like that be used? Paul _______________________________________________ Python-ideas mailing list Python-ideas@python.org https://mail.python.org/mailman/listinfo/python-ideas Code of Conduct: http://python.org/psf/codeofconduct/