[squeak-dev] Re: How to have a fast and usable Date? (was: new
Bug in Locale)
casey.obrien.r at gmail.com
Fri Feb 3 02:43:45 UTC 2012
Top post: What he said. Or maybe we move the timezone specific stuff down a notch in the hierarchy, and have a class above it that just does fast UTC, but please don't take it out. It's one of those wonderful things most systems don't have.
+1 for Dave's argument. Besides, I can't get a date to save my life!
On Feb 2, 2012, at 1:01 PM, "David T. Lewis" <lewis at mail.msen.com> wrote:
> On Thu, Feb 02, 2012 at 02:50:56PM -0500, Yanni Chiu wrote:
>> On 02/02/12 11:25 AM, Chris Muller wrote:
>>> Best to strip all Dates (NOT DateAndTimes) of their timezone.
>> IMHO, there are two different concepts getting mixed up.
>> 1) There is a "date", which has a day, month and year (and calendar). If
>> you're modeling dates to be printed on a 12-month calendar that can be
>> used anywhere in the world, then this is the kind of date you want.
> Yes, I think that was more or less the original implementation in earlier
> Squeak before Chronology was added.
>> 2) There is the 24hr period (sometimes 23hr or 25hr) which corresponds
>> to that "date". This 24hr period is timezone dependent. If you're making
>> a scheduling application, then this is the kind of date you need.
> Yes, and this is the meaning of "date" in more recent Squeak.
>> So, i agree: remove timezone from Date.
> Date does not have a timezone. It has a start DateAndTime, which in
> turn has an offset from UTC. Neither Date nor DateAndTime has a timezone.
>>> I propose Date's, by default, be created with the UTC offset, NOT the
>>> local offset.
>> Disagree. The natural default for today, is the date in my local
>> timezone. Maybe #todayUTC should be introduced. Then why not add
>> #todayInTimezone: too. Hmm...timezones seem to be creeping back in.
> And more generally, don't change it at all unless we can clearly
> state the (new?) meaning of "date" and write it down in a class
> comment for all to see and understand. A "date" may mean very
> different things in the context of different use cases, so if
> there is an interest in making something with a different meaning,
> it suggests that a different class should be invented. There is
> also an ANSI Smalltalk definition to keep in mind here.
> p.s. I just ran the unit tests for TimeZoneDatabase and see new
> failures, but only when running on the standard interpreter. Did
> we change something in the image in a Cog-dependent way? I'll track
> it down as soon as I get some time but if someone can point me to
> the answer I'd appreciate it.
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