On Mon, Jun 27, 2016 at 5:30 AM, David T. Lewis <lewis at mail.msen.com> wrote:

> A bit off topic, but is is worth asking:
> If we really want to model Date as a position on a continuum of date
> values, and if we think that the implementation of Date as a kind of
> Timespan is not right, then shouldn't we just consider going back to
> the earlier (Squeak 3.6 and earlier) implementation of Date as a Magnitude,
> rather than Date as a Timespan?
>

I think this is a very relevant question. We may have to distinguish a Day
from a Date.

IMHO a birthday is a perfect example. It's defined by a day+month+year. If
I was traveling I would celebrate the birthday in local time, so the
generic "birthday" needs to compare equal to all the local dates
independent of time zone.

This is how Dates worked before we made them Timespans (because they had no
time, and hence no time zone). And this is also how they worked after I
added the "nil" offset hack (which ignores the timezone). But it's a hack,
not a good design. I'm not entirely sure what a good design would look like
that also does not break old code.

- Bert -
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