[Datetime-SIG] PEP 495 (Local Time Disambiguation) is ready for pronouncement

Guido van Rossum guido at python.org
Mon Sep 21 23:54:41 CEST 2015


On Sun, Sep 20, 2015 at 8:49 PM, Alexander Belopolsky <
alexander.belopolsky at gmail.com> wrote:

> On Sat, Aug 15, 2015 at 8:49 PM, Alexander Belopolsky <
> alexander.belopolsky at gmail.com> wrote:
> >
> > PEP 495 [1] is a deliberately minimalistic proposal to remove an
> > ambiguity in representing some local times as datetime.datetime
> > objects.
>
> A major issue has come up since my announcement above.  Tim Peters have
> noticed that PEP 495 would violate the "hash invariant" unless the fold
> attribute is accounted for in inter-zone comparisons.
> See [2] for details.  This issue has been resolved by modifying the
> definition [3] of the "==" operator for aware datetimes with post-PEP
> tzinfo.  Note that no program will be affected by this change unless it
> uses a post-PEP tzinfo implementation.
>
> I made some smaller changes [4] to the PEP as well and it should finally
> be ready for pronouncement.
>
> [1]: https://www.python.org/dev/peps/pep-0495
> [2]:
> https://mail.python.org/pipermail/datetime-sig/2015-September/000625.html
> [3]:
> https://www.python.org/dev/peps/pep-0495/#aware-datetime-equality-comparison
> [4]: https://hg.python.org/peps/log/39b7c1da05a2/pep-0495.txt
>

I've reviewed this latest version and I am hereby accepting it. The topic
is both controversial and yawn-inducing, so I think it's better not to give
the usual one-day warning on python-dev -- I'll just post my decision there.

Alexander and Tim, thank for all your work on this! It's been a wild, wild
ride. (And no, I am not going to make a joke about leap seconds here. :-)

-- 
--Guido van Rossum (python.org/~guido)
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