[DB-SIG] DateTime: Changing the time value handling ?!

Jim Fulton jim.fulton@digicool.com
Wed, 11 Mar 1998 10:49:42 -0500

M.-A. Lemburg wrote:
> Jim Fulton wrote:
> >
> > Greg Stein (Exchange) wrote:
> > >
> >
> > The ODMG standard includes time zone in it's Time and Timestamp classes.
> > They take a fairly minimalist approach.  Their time zones are just
> > offsets
> > from UTC.  They leave deciding *what* the offset is (e.g. dealing with
> > daylight savings time) to the application.
> >
> > > I would highly recommend the absolute avoidance of anything that infers /
> > > implies time zones within the base data types.
> >
> > I disagree with this statement, although not entirely.  As I have
> > said before, I think the Date-Time classes should be based on the
> > ODMG standard which provides a *mimimalish*, but useful, treatment
> > of time zones.
> I think Greg meant the low-level implementation of DateTime objects.

So did I.  I think that the low-level data structure should store 
an *offset from UTC*. I thik that determination and interpretation
of the offset should be left to the application.  Of course, 
applications that don't care about the offset could ignore it.

In my implementation of the ODMG Date, Time, Timestamp, and Interval 
classes (currently a low-priority project of mine), dates and
times are stored as local time and an offset.  Since the offset
is optional, applications can ignore it, but it can be obtained by
apps that care and is used in date-time arithmetic. I don't worry
about "ticks" in my implementation, as I store date/time components
directly, rather than as offsets from some time.


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