[squeak-dev] The Trunk: Kernel-cmm.992.mcz

Bert Freudenberg bert at freudenbergs.de
Thu Feb 18 22:35:54 UTC 2016

> On 18.02.2016, at 14:17, Chris Muller <asqueaker at gmail.com> wrote:
>>> In addition, the creation of Dates with Date today must not have a TZ
>>> specified.  Your change broke that and I've added a test.
>> This is a very arbitrary requirement you are imposing there. There is no DateAndTime without timezone. A zero offset does not mean “no timezone” but it means “UTC”.
> There is no DateAndTime without a TZ, but there are *Dates* without
> TZ's.  There have been several discussions on the Squeak and Pharo
> lists about this, it is not an arbitrary requirement in the least.
> People want Dates without timezones more often than they want them
> with.
> Remember yesterday you mentioned how having another Date class to
> support TZ's could be confusing?  I agree!  Well, with Chronology, we
> don't need two, because it implements a Date as a Timespan with a
> duration of 1-day.  So this brilliantly supports both families of
> use-cases simultaneously; the ones that want to do *scheduling* (with
> TZ's) and the ones that simply want Date positions (or Hour positions
> or Minute positions), that compare quickly and successfully with other
> Date/Hour/Minute positions (because Chronology implements those with
> underlying offset of 0:00:00).

An offset of 0 in Chronology means that point in time is given in UTC. It does not mean there is no timezone.

> When I'm dealing with Dates as positions, I ignore the underlying
> DateAndTime and its TimeZone.  It's just for Chronology's
> implementation, which I don't need or want to concern myself with.
>> It may very well be that we do want a Date without a Timezone. That’s why we need a rewrite of Chronology that allows that, and makes it explicit.
> Timespan class>>#current explicitly specifies the #defaultOffset,
> which has a detailed comment.

Yes, that’s why I changed the equality check in Timespan to check for the defaultOffset and in that case ignore the time zone. I’ll do the same for magnitude comparison, which makes all tests green again. It’s the best we can do for now I think.

- Bert -

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