[Python-Dev] TZ-aware local time (original) (raw)

Alexander Belopolsky alexander.belopolsky at gmail.com
Mon Jun 11 15:33:11 CEST 2012

On Fri, Jun 8, 2012 at 11:06 PM, Guido van Rossum <guido at python.org> wrote:

On Fri, Jun 8, 2012 at 2:08 PM, Alexander Belopolsky <alexander.belopolsky at gmail.com> wrote: ..

t = mktime((2010, 11, 7, 1, 0, 0, -1, -1, 0)) for i in range(5): ...     print(strftime("%T%z", localtime(t + i - 2))) ... 01:59:58-0400 01:59:59-0400 01:00:00-0500 01:00:01-0500 01:00:02-0500 As I explained at <http://bugs.python.org/msg109452>, it is not possible to reproduce this sequence using LocalTimezone. So LocalTimezone (or any named timezone that uses DST) should not be used for this purpose. .. I'm still unsure what problem you're trying to solve.

The problem is: produce a timestamp (e.g. RFC 3339) complete with timezone information corresponding to the current time or any other unambiguously defined time. This is exactly what my proposed datetime.localtime() function does.

Can we just introduce LocalTimezone (or whatever name it should have) and let the issue rest?

No. LocalTimezone adresses a different problem and does not solve this one. If you generate a timestamp using datetime.now(LocalTimezone).strftime("... %z"), your timestamps will be wrong for one hour every year. Some users may tolerate this, but the problem is not hard to solve and I think datetime module should offer one obvious and correct way to do it.

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