Re: [Scheme-reports] current-posix-second is a disastrous mistake

[Alex Shinn <alexshinn@x>]

On Wed, Dec 15, 2010 at 3:09 AM, Vitaly Magerya <vmagerya@x> wrote:
> On 2010-12-15 12:22, Alaric Snell-Pym wrote:
>>> You can't use TAI to represent dates in the future,
>>> as it would require leap seconds tables that are only published six
>>> months before the leap seconds occur.
>>
>> But we're not trying to represent dates; we're trying to represent the
>> pssage of time.
>
> Any monotonic clock with unspecified origin is sufficient to represent
> passage of time. What Alex suggested was to use TAI clock specifically
> to represent both passage of time and UTC (civil time, wall clock time,
> "date", call it as you wish).

I said no such thing.  I'm suggesting using TAI to represent an
unambiguous point on a timeline, and presumably a record-like
data type for dates.

We use monotonic seconds primarily for timestamps and timeouts
(i.e. times in the very near future).  If you wanted to compute a
date-time in the distant future and store it as TAI time, then your
point about not knowing future leap seconds is valid.  However,
if you computed that time via second-interval arithmetic (i.e. you
want exactly n seconds in the future) you'd be guaranteed to
have the same loss in precision using POSIX time.

-- 
Alex

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