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Remove time.accept2dyear #56139

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Remove time.accept2dyear#56139
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extension-modulesC modules in the Modules dirstdlibStandard Library Python modules in the Lib/ directorytype-featureA feature request or enhancement

Description

@abalkin
abalkin
opened on Apr 26, 2011
BPO 11930
Nosy @abalkin, @vstinner
Files
  • remove-accept2dyear.diff
  • datetime_y2k.patch
    		•

    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 2011-05-02.17:17:26.562>
created_at = <Date 2011-04-26.19:37:41.759>
labels = ['extension-modules', 'type-feature', 'library']
title = 'Remove time.accept2dyear'
updated_at = <Date 2011-05-02.21:04:16.168>
user = 'https://github.com/abalkin'

    bugs.python.org fields:

    activity = <Date 2011-05-02.21:04:16.168>
actor = 'vstinner'
assignee = 'none'
closed = True
closed_date = <Date 2011-05-02.17:17:26.562>
closer = 'belopolsky'
components = ['Extension Modules', 'Library (Lib)']
creation = <Date 2011-04-26.19:37:41.759>
creator = 'belopolsky'
dependencies = []
files = ['21785', '21788']
hgrepos = []
issue_num = 11930
keywords = ['patch']
message_count = 13.0
messages = ['134493', '134507', '134508', '134509', '134512', '134516', '134517', '134520', '134933', '134988', '134993', '134996', '135008']
nosy_count = 3.0
nosy_names = ['belopolsky', 'vstinner', 'python-dev']
pr_nums = []
priority = 'normal'
resolution = 'accepted'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue11930'
versions = ['Python 3.3']

    Activity

    1. abalkin commented on Apr 26, 2011

      @abalkin
      abalkin
      on Apr 26, 2011
      MemberAuthor

      As implemented in bpo-10827, use of 2-digits years in timetuples to mean 4-digit years straddling year 2000 is deprecated in 3.3. There is no mechanism for issuing deprecation warning for access to a module variable, but a deprecation note was added to its documentation.

      Attached patch removes time.accept2dyear and the associated behaviors.

    2. abalkin
      added
      type-featureA feature request or enhancement
      on Apr 26, 2011

    3. vstinner commented on Apr 26, 2011

      @vstinner
      vstinner
      on Apr 26, 2011
      Member

      time.rst:

      • **Year 2000 (Y2K) issues**: Python depends on the platform's C library, which
        generally doesn't have year 2000 issues, since all dates and times are
        represented internally as seconds since the epoch. Function :func:`strptime`
        can parse 2-digit years when given ``%y`` format code. When 2-digit years are
        parsed, they are converted according to the POSIX and ISO C standards: values
        69--99 are mapped to 1969--1999, and values 0--68 are mapped to 2000--2068.

      .. class:: struct_time (...) A year value will be handled as described under :ref:`Year 2000 (Y2K) issues <time-y2kissues>` above.

      .. [#] The use of ``%Z`` is now deprecated, but the ``%z`` escape that expands to the
      preferred hour/minute offset is not supported by all ANSI C libraries. Also, a
      strict reading of the original 1982 :rfc:`822` standard calls for a two-digit
      year (%y rather than %Y), but practice moved to 4-digit years long before the
      year 2000. The 4-digit year has been mandated by :rfc:`2822`, which obsoletes
      :rfc:`822`.

      Are these 3 notes still valid? It looks like struct_time note is wrong: the year 70 is now 70 and not interpreted as 1970 anymore.

      ---

      timemodule.c:

      PyDoc_STRVAR(module_doc,
      "...
      The tuple items are:\n\
      year (four digits, e.g. 1998)\n\
      ...")

      => That's wrong. Example: time.gmtime(-55582200000).tm_year gives 208.

      ---

      /home/haypo/prog/HG/cpython/Modules/timemodule.c: In function 'PyInit_time':
      /home/haypo/prog/HG/cpython/Modules/timemodule.c:872: warning: unused variable 'p'

    4. abalkin commented on Apr 26, 2011

      @abalkin
      abalkin
      on Apr 26, 2011
      MemberAuthor

      On Tue, Apr 26, 2011 at 6:09 PM, STINNER Victor <report@bugs.python.org> wrote:

      It looks like struct_time note is wrong: the year 70 is now 70 and not interpreted as 1970 anymore.

      What makes you say so?

      1970

    5. abalkin commented on Apr 26, 2011

      @abalkin
      abalkin
      on Apr 26, 2011
      MemberAuthor

      On Tue, Apr 26, 2011 at 6:09 PM, STINNER Victor <report@bugs.python.org> wrote:
      ..

      timemodule.c:

      PyDoc_STRVAR(module_doc,
      "...
      The tuple items are:\n\
       year (four digits, e.g. 1998)\n\
      ...")

      => That's wrong. Example: time.gmtime(-55582200000).tm_year gives 208.

      This is wrong regardless of this patch. I don't mind fixing this,
      but it would be a different issue. Can you suggest a change? I would
      like the docstring to still inform the user that 1998 should be given
      as 1998 and not as 98. Maybe s/four/all/?

    6. vstinner commented on Apr 26, 2011

      @vstinner
      vstinner
      on Apr 26, 2011
      Member

      "What makes you say so?

      1970"

      Don't write ">>> " using the email interface :-)

      --

      >>> t
time.struct_time(tm_year=70, tm_mon=1, tm_mday=1, tm_hour=0, tm_min=0, tm_sec=0, tm_wday=3, tm_yday=1, tm_isdst=0)
>>> time.mktime(t)
-59958144561.0
>>> time.localtime(_)
time.struct_time(tm_year=70, tm_mon=1, tm_mday=1, tm_hour=0, tm_min=0, tm_sec=0, tm_wday=2, tm_yday=1, tm_isdst=0)

      Year 70 is considered as the year 70.

    7. abalkin commented on Apr 26, 2011

      @abalkin
      abalkin
      on Apr 26, 2011
      MemberAuthor
      On Tue, Apr 26, 2011 at 6:30 PM, STINNER Victor <report@bugs.python.org> wrote:
>
> STINNER Victor <victor.stinner@haypocalc.com> added the comment:
>
> "What makes you say so?
>
> 1970"
>
> Don't write ">>> " using the email interface :-)
>

      Sorry. That was the output of time.strptime('70', '%y')[0].

    8. abalkin commented on Apr 26, 2011

      @abalkin
      abalkin
      on Apr 26, 2011
      MemberAuthor

      On Tue, Apr 26, 2011 at 6:09 PM, STINNER Victor <report@bugs.python.org> wrote:
      ..

      .. class:: struct_time (...) A year value will be handled as described under :ref:`Year 2000 (Y2K) issues <time-y2kissues>` above.

      This one needs to be removed. Thanks.

    9. vstinner commented on Apr 26, 2011

      @vstinner
      vstinner
      on Apr 26, 2011
      Member

      The next step is to update the datetime module: something like the attached patch (datetime_y2k.patch).

    10. vstinner commented on May 1, 2011

      @vstinner
      vstinner
      on May 1, 2011
      Member

      Le mardi 26 avril 2011 à 22:20 +0000, Alexander Belopolsky a écrit :

      Alexander Belopolsky <belopolsky@users.sourceforge.net> added the comment:

      On Tue, Apr 26, 2011 at 6:09 PM, STINNER Victor <report@bugs.python.org> wrote:
      ..
      >
      > timemodule.c:
      >
      > PyDoc_STRVAR(module_doc,
      > "...
      > The tuple items are:\n\
      > year (four digits, e.g. 1998)\n\
      > ...")
      >
      > => That's wrong. Example: time.gmtime(-55582200000).tm_year gives 208.

      This is wrong regardless of this patch. I don't mind fixing this,
      but it would be a different issue. Can you suggest a change? I would
      like the docstring to still inform the user that 1998 should be given
      as 1998 and not as 98. Maybe s/four/all/?

      "year (e.g. 1998)\n" is enough.

    11. python-dev commented on May 2, 2011

      @python-dev
      python-devmannequin
      on May 2, 2011
      Mannequin

      New changeset e6f6ac8c2502 by Alexander Belopolsky in branch 'default':
      Issue bpo-11930: Remove deprecated time.accept2dyear.
      http://hg.python.org/cpython/rev/e6f6ac8c2502

    12. python-dev commented on May 2, 2011

      @python-dev
      python-devmannequin
      on May 2, 2011
      Mannequin

      New changeset db2ac3dc6cc2 by Alexander Belopolsky in branch 'default':
      Issue bpo-11930: Remove year >= 1000 limitation from datetime.strftime.
      http://hg.python.org/cpython/rev/db2ac3dc6cc2

    13. abalkin
      added
      extension-modulesC modules in the Modules dir
      stdlibStandard Library Python modules in the Lib/ directory
      on May 2, 2011
    14. abalkin
      closed this as completedon May 2, 2011

    15. python-dev commented on May 2, 2011

      @python-dev
      python-devmannequin
      on May 2, 2011
      Mannequin

      New changeset bfd741162741 by Alexander Belopolsky in branch 'default':
      Issue bpo-11930: Added Misc/NEWS and versionchanged entries.
      http://hg.python.org/cpython/rev/bfd741162741

    16. vstinner commented on May 2, 2011

      @vstinner
      vstinner
      on May 2, 2011
      Member

      New changeset e6f6ac8c2502 by Alexander Belopolsky in branch 'default':
      Issue bpo-11930: Remove deprecated time.accept2dyear.

      Great!

    17. ezio-melotti
      transferred this issue fromon Apr 10, 2022
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