wrong time.timezone

[4kir4]

BPO	22799
Nosy	@abalkin, @4kir4
Superseder	bpo-28157: Document time module constants (timezone, tzname, etc.) as deprecated.

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2016-09-14.19:08:31.361>
created_at = <Date 2014-11-05.15:00:06.276>
labels = ['type-bug', 'library']
title = 'wrong time.timezone'
updated_at = <Date 2016-09-14.19:17:21.797>
user = 'https://github.com/4kir4'

bugs.python.org fields:

activity = <Date 2016-09-14.19:17:21.797>
actor = 'belopolsky'
assignee = 'none'
closed = True
closed_date = <Date 2016-09-14.19:08:31.361>
closer = 'belopolsky'
components = ['Library (Lib)']
creation = <Date 2014-11-05.15:00:06.276>
creator = 'akira'
dependencies = []
files = []
hgrepos = []
issue_num = 22799
keywords = []
message_count = 7.0
messages = ['230684', '231754', '234893', '234901', '234905', '234907', '276476']
nosy_count = 2.0
nosy_names = ['belopolsky', 'akira']
pr_nums = []
priority = 'normal'
resolution = 'wont fix'
stage = None
status = 'closed'
superseder = '28157'
type = 'behavior'
url = 'https://bugs.python.org/issue22799'
versions = ['Python 3.4', 'Python 3.5', 'Python 3.6']

[4kir4]

$ TZ=:Europe/Moscow ./python -mtest -v test_time
  

======================================================================
FAIL: test_localtime_timezone (test.test_time.TestPytime)
----------------------------------------------------------------------

  Traceback (most recent call last):
    File ".../Lib/test/test_time.py", line 721, in test_localtime_timezone
      self.assertEqual(lt.tm_gmtoff, -[time.timezone, time.altzone][lt.tm_isdst])
  AssertionError: 10800 != 14400
  
  

---

Ran 45 tests in 1.832s

FAILED (failures=1, skipped=3)
test test_time failed
1 test failed:
test_time

UTC offset had changed on 2014-10-26 in Europe/Moscow timezone from
MSK+0400 to MSK+0300.

Python time.timezone returns -14400 (old utc offset) despite C timezone
variable having the correct value (Python uses tm_gmtoff from Jan here).

Similar case where timezone, altzone may be wrong
http://bugs.python.org/msg31138

The issue again http://bugs.python.org/issue22798 is that time timezone
attribute is out-of-sync with the corresponding C variable i.e., C
library provides correct values but time module doesn't use them.

[4kir4]

This issue could be fixed using sync-time-timezone-attr-with-c.diff patch from http://bugs.python.org/issue22798

[abalkin]

Isn't this a duplicate of bpo-13466?

[4kir4]

Isn't this a duplicate of bpo-13466?

In what way is it a duplicate?

[abalkin]

Please take a look at msg148208. I agree with MAL that time module globals timezone and daylight should be deprecated in favor of tm_gmtoff or datetime.astimezone().

[4kir4]

I agree that time.timezone, time.altzone is not enough in the general
case. Because UTC offset may be different at different dates for
reasons unrelated to DST transitions therefore any solution that
doesn't take into account a given date/time into account will fail.

*Nothing* works in the general case. Nothing.

But it doesn't mean that the current behaviour of time.timezone
can't be improved for this particular use-case:

  lt = time.localtime() # in a short-lived script
  assertEqual(lt.tm_gmtoff, -[time.timezone, time.altzone][lt.tm_isdst])

The test checks values for the current time (time.localtime()).
It should work in *most* cases if time.timezone/altzone have correct
values at import time.

Perhaps synchronizing time.timezone with C timezone variable as I've
mentioned before http://bugs.python.org/issue22798 may fix this issue
too.

[abalkin]

Closing. See bpo-22798 for the reasons why synchronizing C variables with the time module constants is not a solution.