[REBOL] Re: Daylight saving (Was: RE: Re: Swatch time)
From: sanghabum:aol at: 8-Oct-2001 11:58
[Mario--Cassani--icl--com] writes:
> The timezones/daylight handling makes me crazy, I am never
> sure windows gives the right time, it looks like the BIOS and
> windows use two different clocks...
If this sort of thing doesn't drive you crazy, then there must be something
wrong with you. The rules are completely arbitrary and geopolitical. Windows
implements only a tiny subset of the global rules needed for an accurate
daylight savings change over.
To do it accurately, you need to know which country you are in. If you are in
the USA there are different rules per state (some do not have DSL at all)
and, for Indiana, there are different rules per county.
Once you know your locale (country, state, county, whatever) the date that
DSL kicks in or out is either decided by a simple rule (s in the USA or by a
dithery committee (as in the UK—where diaries always say "sorry we were
printed too far ahead to be 100% accurate about the Summer Time change date").
And then, fuinally, I think, you need to know the time of day for the
changeover in that locale--it isn't always 02:00.
Ed Nisley has a good starter article in this month's Dr Dobbs, but he really
only covers the USA:
http://www.ddjembedded.com/resources/articles/2001/0110m/0110m.htm
If you really want to be driven mad, try working for a flight operator with
flights from Country A to Country C with a touchdown in country B. And then
try to be accurate about the actual local times of takeoff/landing during the
month or so when DSL wafts across the world.
--I've tried it. I'm gibbering,
--Colin.
