Mailman 3 October 2015 - Datetime-SIG

Re: [Datetime-SIG] Visualizing the DST transitions
by Carl Meyer 21 Oct '15

21 Oct '15

On 10/21/2015 03:27 PM, Alexander Belopolsky wrote: > I just wanted to share a slide > <https://docs.google.com/presentation/d/1H1tkvg_vm39jXPZbOvQLoWb32POSpTYiZx8…> > [1] I came across that is very similar to the sketches in PEP 495. Does > anyone understand how CCTZ handles the discontinuities? It provides two APIs, MakeTime and MakeTimeInfo, which both accept a "naive datetime" and a timezone. MakeTime returns an absolute time, and discontinuities are handled by always assuming the pre-transition offset: https://github.com/google/cctz/blob/master/src/cctz.h#L131 MakeTimeInfo returns a more complex TimeInfo struct which has a `kind` enum member that can be `UNIQUE` (the normal case), `SKIPPED`, or `REPEATED`, and has `pre`, `post`, and `trans` timestamp members (containing the time calculated using the pre-transition offset, the time calculated using the post-transition offset, and the time at which the transition occurs), which in the normal case of `UNIQUE` are all set to the same value. Documentation starts here: https://github.com/google/cctz/blob/master/src/cctz.h#L142 Carl

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Re: [Datetime-SIG] Visualizing the DST transitions
by Alexander Belopolsky 21 Oct '15

21 Oct '15

On Wed, Oct 21, 2015 at 5:29 PM, Guido van Rossum <guido(a)python.org> wrote: > Heh, they swapped the X and Y axes. :-) Right, but despite that, it looks like they use the same default rules for local to absolute conversions as we do in PEP 495 datetime.timestamp().

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Re: [Datetime-SIG] Visualizing the DST transitions
by Guido van Rossum 21 Oct '15

21 Oct '15

Heh, they swapped the X and Y axes. :-) On Wed, Oct 21, 2015 at 2:27 PM, Alexander Belopolsky < alexander.belopolsky(a)gmail.com> wrote: > I just wanted to share a slide > <https://docs.google.com/presentation/d/1H1tkvg_vm39jXPZbOvQLoWb32POSpTYiZx8…> > [1] I came across that is very similar to the sketches in PEP 495. Does > anyone understand how CCTZ handles the discontinuities? > > [1]: > https://docs.google.com/presentation/d/1H1tkvg_vm39jXPZbOvQLoWb32POSpTYiZx8… > > _______________________________________________ > Datetime-SIG mailing list > Datetime-SIG(a)python.org > https://mail.python.org/mailman/listinfo/datetime-sig > The PSF Code of Conduct applies to this mailing list: > https://www.python.org/psf/codeofconduct/ > -- --Guido van Rossum (python.org/~guido)

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Visualizing the DST transitions
by Alexander Belopolsky 21 Oct '15

21 Oct '15

I just wanted to share a slide <https://docs.google.com/presentation/d/1H1tkvg_vm39jXPZbOvQLoWb32POSpTYiZx8…> [1] I came across that is very similar to the sketches in PEP 495. Does anyone understand how CCTZ handles the discontinuities? [1]: https://docs.google.com/presentation/d/1H1tkvg_vm39jXPZbOvQLoWb32POSpTYiZx8…

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Add strptime directives to parse ISO calendar dates
by Alexander Belopolsky 02 Oct '15

02 Oct '15

This feature has been proposed four years ago and a complete patch is available at the bug tracker. [1] I think this is a nice feature to have and the latest patch looks good, but it will be helpful to have the patch reviewed by someone who will actually benefit from this feature. [1]: http://bugs.python.org/issue12006

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