The status of PEP 555 is just a side track. Here, I took a step back compared to what went into PEP 555.
—Koos On Wed, Jan 10, 2018 at 6:21 PM, Guido van Rossum <gu...@python.org> wrote: > The current status of PEP 555 is "Withdrawn". I have no interest in > considering it any more, so if you'd rather see a decision from me I'll be > happy to change it to "Rejected". > > On Tue, Jan 9, 2018 at 10:29 PM, Koos Zevenhoven <k7ho...@gmail.com> > wrote: > >> On Jan 10, 2018 07:17, "Yury Selivanov" <yselivanov...@gmail.com> wrote: >> >> Wasn't PEP 555 rejected by Guido? What's the point of this post? >> >> >> I sure hope there is a point. I don't think mentioning PEP 555 in the >> discussions should hurt. >> >> A typo in my post btw: should be "PEP 567 (+568 ?)" in the second >> paragraph of course. >> >> -- Koos (mobile) >> >> >> Yury >> >> On Wed, Jan 10, 2018 at 4:08 AM Koos Zevenhoven <k7ho...@gmail.com> >> wrote: >> >>> Hi all, >>> >>> I feel like I should write some thoughts regarding the "context" >>> discussion, related to the various PEPs. >>> >>> I like PEP 567 (+ 567 ?) better than PEP 550. However, besides providing >>> cvar.set(), I'm not really sure about the gain compared to PEP 555 (which >>> could easily have e.g. a dict-like interface to the context). I'm still not >>> a big fan of "get"/"set" here, but the idea was indeed to provide those on >>> top of a PEP 555 type thing too. >>> >>> "Tokens" in PEP 567, seems to resemble assignment context managers in >>> PEP 555. However, they feel a bit messy to me, because they make it look >>> like one could just set a variable and then revert the change at any point >>> in time after that. >>> >>> PEP 555 is in fact a simplification of my previous sketch that had a >>> .set(..) in it, but was somewhat different from PEP 550. The idea was to >>> always explicitly define the scope of contextvar values. A context manager >>> / with statement determined the scope of .set(..) operations inside the >>> with statement: >>> >>> # Version A: >>> cvar.set(1) >>> with context_scope(): >>> cvar.set(2) >>> >>> assert cvar.get() == 2 >>> >>> assert cvar.get() == 1 >>> >>> Then I added the ability to define scopes for different variables >>> separately: >>> >>> # Version B >>> cvar1.set(1) >>> cvar2.set(2) >>> with context_scope(cvar1): >>> cvar1.set(11) >>> cvar2.set(22) >>> >>> assert cvar1.get() == 1 >>> assert cvar2.get() == 22 >>> >>> >>> However, in practice, most libraries would wrap __enter__, set and >>> __exit__ into another context manager. So maybe one might want to allow >>> something like >>> >>> # Version C: >>> assert cvar.get() == something >>> with context_scope(cvar, 2): >>> assert cvar.get() == 2 >>> >>> assert cvar.get() == something >>> >>> >>> But this then led to combining "__enter__" and ".set(..)" into >>> Assignment.__enter__ -- and "__exit__" into Assignment.__exit__ like this: >>> >>> # PEP 555 draft version: >>> assert cvar.value == something >>> with cvar.assign(1): >>> assert cvar.value == 1 >>> >>> assert cvar.value == something >>> >>> >>> Anyway, given the schedule, I'm not really sure about the best thing to >>> do here. In principle, something like in versions A, B and C above could be >>> done (I hope the proposal was roughly self-explanatory based on earlier >>> discussions). However, at this point, I'd probably need a lot of help to >>> make that happen for 3.7. >>> >>> -- Koos >>> >>> _______________________________________________ >>> Python-Dev mailing list >>> Python-Dev@python.org >>> https://mail.python.org/mailman/listinfo/python-dev >>> Unsubscribe: https://mail.python.org/mailma >>> n/options/python-dev/yselivanov.ml%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/guido% >> 40python.org >> >> > > > -- > --Guido van Rossum (python.org/~guido) > -- + Koos Zevenhoven + http://twitter.com/k7hoven +
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