RE: [boost] Date/Time formal review

From: Jeff Garland (jeff_at_[hidden])
Date: 2002-04-17 14:06:54

> >
> > The civil calendar (in particular local time) is governed by the rules
> > of legislators not physics.
>
> What Ross was proposing was a different way to partition the model behind
> the library. As the core of such a model he proposes the purely physical
> aspects which are *not* governed by legislators. This would deal with
> things like points in time and distances (durations) between them. This is
> Physics.

That's fine.  It is an implementation detail that the posix_time uses the gregorian system
internally.  I choose this because of popularity and simplicity, but there is no constraint that
other time systems choose this approach.

> The calendar/time system does not provide the rules for physical
> calculations. The distance between two physical points in time does not
> depend on the calendar used. It depends somewhat on one's relative motion
> and location, but I think we can ignore relativistic effects... :-)

Well it does in GDTL.  Think of the calendar and time systems as a set of policies that govern
things like the mapping of the year-month-day and calculations.  It's easy to implement if you have
a time system that is based on 'physics' with no discontinuities, but this is not the reality for
some.

Jeff