On Thursday, January 30, 2003, at 05:19 PM, Dave Rolsky wrote:
What should happen when someone does this:Be Here Now:
my $dt = ...;
$dt->set( time_zone => 'America/Denver' );
and the new time zone is different from the old?
There's two ways to do this. One is to keep the UTC time the same, which
ends up shifting the effective local time.
The other would be to change the local time (in effect shifting the UTC
time).
2003-01-30 15:30:00 Chicago
These operations argue for constant UTC, shifted local time:
When this shipment reaches Denver in 6 hours, what time will it be there?
Schedule a conference call for people in Chicago, Denver, and London
Map the path of an eclipse across Europe for local viewing
Record a transaction whose parties are in San Francisco and Budapest
I can't think of any yet that argue for shifting UTC, but the trooth is out there...
On Thursday, January 30, 2003, at 05:52 PM, John Peacock wrote:
John, is there a principle that could be stated, behind your 'NSHO'? This seems clear to me, but then I wonder if I'm trapped in some thought rigidity.Store in UTC (always).
Are we always moving with the object in relation to the world the object starts from? All of the above examples have some element of 'right now' in them; e.g., to know what time it will be in Denver when the shipment arrives there, get Denver's time 'right now' and add the shipping time. Fixed UTC, by the nature of the question.
Always the case? I'll take it as a working rule, but it makes me very curious about possible counter-examples...
Especially considering time zones, I'm now convinced that 'time' for us relies on more fictions than even 'money'! [0]
Real time for the universe is seconds since the big bang; for a person, it's what the sundial says outside the front door and how tall the kids have grown. Everything else is layers of symbols, schemes and schedules.
I guess I'm going on about this as a way of expressing appreciation for Dave and others who have risen to turn convoluted fiction into logic.
- got time zone stuff working (see previous message which no one responded
to. sniff)
I'm in a different TZ ;-)
[0] Although money relies on time... - Bruce __bruce__van_allen__santa_cruz__ca__
