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From: reinkor <reinkor@gmail.com>
Newsgroups: comp.lang.ada
Subject: Re: Newbie Q: How to program in UTC (time/calendar) ?
Date: Wed, 25 Mar 2009 03:21:45 -0700 (PDT)
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Date: 2009-03-25T03:21:45-07:00
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On 25 Mar, 00:59, Martin <martin.do...@btopenworld.com> wrote:
> On Mar 24, 6:53=A0pm, Dirk Heinrichs <dirk.heinri...@online.de> wrote:
>
> > Martin wrote:
> > > These sort of things make sensible time computations hard, e.g. what
> > > does "1:30am" mean if the clocks have gone back an hour for winter at
> > > 2am? Is it the first 1:30am or the second that night?
>
> > I'd say that depends on the OS you run your program on (and its
> > configuration).
>
> Exactly - and the times in the original question may not even have
> come from the computer doing the calculations - they could be a log
> from e.g. a Sat Nav - what would it be doing?
>
> Cheers
> -- Martin

I did hope I could use the Ada calendar routines to process
"historical" data tagged with UTC - independent of where
in the world I run the program.

I (at least) want my computations to be independent of the local
time of the computer. My program should e.g. give the same result
when running on a computer in Alaska or Australia. 2 + 2 =3D 4 all
over the world ! :-)  And I was born 12 March UTC independet of
the "local time" of my computer !

Yes, I know that UTC has its weakness that has to be considered
in applications. Anyway, when giving an UTC date/time to a computer
program, this should not be affected if the computer change time zone
when processing? A travelling computer may run a program many days
and while it is passing many time zones.  Consider, for examlpe,
a web camera/sensor related program on a car/truck driving from coast
to coast in USA or Canada !  One has frequently to update
UTC_Time_Offset
in order to handle input data correct if one wants to tagg events
with UTC?

reinert