On Wed, Jan 4, 2017 at 9:36 PM, Steve Summit <scs...@eskimo.com> wrote: > Warner Losh wrote: >> Steve Summit <scs...@eskimo.com> wrote: >> > The requirement for tables (and, correspondingly, the >> > "impossibility" of dealing with future UTC dates more than a few >> > months out) depends on what you're trying to do... >> > In particular, if right now it's 2017-01-05T01:56:13, I can >> > obviously compute that (say) exactly three years from now is >> > 2020-01-05T01:56:13, and I can even set a computer alarm to >> > go off then, even if neither I nor the (suitably programmed) >> > OS kernel that's tracking the alarm know in advance how many >> > leap seconds there might end up being between now and then. >> >> Except that's not how things are programmed... People can talk >> about it, but computers don't always store things that way. The >> non-uniform radix presents problems. Trying to play semantic games >> like this doesn't change that. There's problem, and trying to >> equivocate away by saying "well, if you just did it right it would be >> OK" isn't a helpful position. Requiring every computer to do >> complicated things so that a leap second can work once in a blue moon >> isn't a good engineering tradeoff. > > Indeed. Did you see the message a few hours ago where I > mentioned the "New Jersey approach" (aka "Worse is better")? > > But my point, my quibble with tvb's list, was that he said that > some things were impossible or require leap second tables, when > in fact they're merely difficult (to the point, depending on your > engineering tradeoffs, of being a bad idea) or sometimes require > leap second tables. > > I don't think that saying something is impossible, when it's > merely difficult, is helpful either.
Saying something is impossible is just a short hand for "impossible to implement efficiently" which is a decidedly helpful thing to say. Forcing a design that can't be fast will inevitably result in a competing design that is fast winning out, even in the face of correctness. time_t is one such example: It made it easy to do local time and literally impossible to do UTC. Warner _______________________________________________ LEAPSECS mailing list LEAPSECS@leapsecond.com https://pairlist6.pair.net/mailman/listinfo/leapsecs
