Re: Inspiration for a better calendar package?

["Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>]

On Wed, 17 Dec 2008 07:16:48 +0100, Wilhelm Spickermann wrote:

> Dmitry A. Kazakov wrote:
> 
>> On Tue, 16 Dec 2008 06:50:40 +0100, Wilhelm Spickermann wrote:
>> 
>>> We need it, because someone in some plant has to specify a
>>> report to be printed on the 1-jul-2009 00:00 UTC. You cannot
>>> tell him, that he should wait a month from now until the IERS
>>> has published it's decision about leap second insertion at the
>>> end of next June.
>> 
>> No we don't. You cannot show a code that neither:
>> 
>> 1. Waits a fixed amount of time (delay until)
>> 
>> 2. Periodically polls actual time (delay delta, look at the
>> time).
>> 
>> There is simply no other way to determine if the report has to
>> be printed. In either case you don't need another "time."
>> 
>> It can be shown even simpler, printing is an action in real
>> time. You cannot present any physical action that happens in
>> political time.
>> 
>> Political fictions are incomputable. (:-))
> 
> Hmmm, now some secretary is trying to type in the dates of her
> next summer holiday and the computer tells her "Cannot do it,
> it's just a political fiction"? :-)
> 
> The program would first wait for about 3 months and then try to
> convert the "wall time" into a "time". If it is still impossible
> then, because the leap second second tables weren't updated, the
> program should give a warning and perhaps rescedule the check. 

You don't need wall time for this. That is the case no.2, I mentioned
above, programmed as follows:

delay 60.0 * 60.0 * 24.0 * 30.0 * 3; -- three physical months
if Month (Clock) = ... and Day (Clock) = ... then
   -- do things
else
   -- give warning
end if;

Where is any problem? Except that the algorithm is not good. It should be
(still the case 2):

   delay 60.0 * 60.0 * 24.0 * 25.0 * 3; -- come close enough to judge
   delay until Time_Of (Year =>..., Month =>..., Day =>...);
   -- do things
exception
   when Time_Error =>  -- watch your fingers lady!

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de