FAQ
Folks,

I know this is going to seem like a dumb question, but please bear with me.

What consequences will PERL programmers face with DateTime, particularly with time zone handling and calculations, if they are still using v5.08 of PERL and the DateTime version that came with that (which I believe dates to v5.06 of PERL).

Regards,
Juan

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  • Jonathan Leffler at Jul 17, 2014 at 3:21 pm
    You'll be stuck with the time zone rules as of the period when the
    DateTime::TimeZone modules were generated, based on the Olson database that
    was used.

    It means that if you try to check the time for somewhere but the rules now
    in effect are different from the ones in effect back then, you will get
    different results for what the time zone offset is, or when the transitions
    between winter and summer (standard and daylight saving) times occur.

    In extreme cases, this could be a whole day off; one country relatively
    recently switched from one side to the other side of the international date
    line.

    Note that the rules change multiple times a year (somewhere in the world,
    some country changes the rules, often at close to the last minute). There
    were at least 9 releases of the Olson database in 2013 and 2012; 14 in 2011
    and 2010; 19 in 2009 (and at least 5 so far in 2014).


    On Thu, Jul 17, 2014 at 7:43 AM, Juan Jimenez wrote:

    Folks,

    I know this is going to seem like a dumb question, but please bear with
    me.

    What consequences will PERL programmers face with DateTime, particularly
    with time zone handling and calculations, if they are still using v5.08 of
    PERL and the DateTime version that came with that (which I believe dates to
    v5.06 of PERL).

    Regards,
    Juan


    --
    Jonathan Leffler <jonathan.leffler@gmail.com> #include <disclaimer.h>
    Guardian of DBD::Informix - v2013.0521 - http://dbi.perl.org
    "Blessed are we who can laugh at ourselves, for we shall never cease to be
    amused."
  • Juan Jimenez at Jul 17, 2014 at 3:48 pm
    Thank you. That is exactly what I suspected but I needed some independence evidence to try to prod some movement on this issue. Much appreciated.

    From: Jonathan Leffler <jonathan.leffler@gmail.com
    Date: Thursday, July 17, 2014 at 11:21 AM
    To: Juan Jimenez <jjimenez@electric-cloud.com
    Cc: "datetime@perl.org " <datetime@perl.org
    Subject: Re: Q about versions

    You'll be stuck with the time zone rules as of the period when the DateTime::TimeZone modules were generated, based on the Olson database that was used.

    It means that if you try to check the time for somewhere but the rules now in effect are different from the ones in effect back then, you will get different results for what the time zone offset is, or when the transitions between winter and summer (standard and daylight saving) times occur.

    In extreme cases, this could be a whole day off; one country relatively recently switched from one side to the other side of the international date line.

    Note that the rules change multiple times a year (somewhere in the world, some country changes the rules, often at close to the last minute). There were at least 9 releases of the Olson database in 2013 and 2012; 14 in 2011 and 2010; 19 in 2009 (and at least 5 so far in 2014).



    On Thu, Jul 17, 2014 at 7:43 AM, Juan Jimenez wrote:
    Folks,

    I know this is going to seem like a dumb question, but please bear with me.

    What consequences will PERL programmers face with DateTime, particularly with time zone handling and calculations, if they are still using v5.08 of PERL and the DateTime version that came with that (which I believe dates to v5.06 of PERL).

    Regards,
    Juan



    --
    Jonathan Leffler <jonathan.leffler@gmail.com #include <disclaimer.h>
    Guardian of DBD::Informix - v2013.0521 - http://dbi.perl.org
    "Blessed are we who can laugh at ourselves, for we shall never cease to be amused."
  • Karen Etheridge at Jul 17, 2014 at 3:45 pm

    On Thu, Jul 17, 2014 at 02:43:41PM +0000, Juan Jimenez wrote:
    Folks,

    I know this is going to seem like a dumb question, but please bear with me.

    What consequences will PERL programmers face with DateTime, particularly with time zone handling and calculations, if they are still using v5.08 of PERL and the DateTime version that came with that (which I believe dates to v5.06 of PERL).
    What do you mean by "the DateTime version that comes with that"? DateTime
    is not a core module - it must always be installed from the CPAN.
    Therefore, it can be upgraded at any time; you are not stuck with an older
    version.

    Or are you perhaps using a linux distribution that packaged a particular
    version of DateTime up with the core perl installation?

    Can you be a bit more specific about the problems that you are seeing? If
    you are only imagining problems, I have a wild imagination and can imagine
    many, but I have enough real problems to keep me busy most of the time that
    I can keep my imagination safely in check. :)

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