Re: ada calendar

[Reinert Korsnes <reinert.korsnes@GETRIDOFSPAMchello.no>]

Nick Roberts wrote:

> Stephen Leake wrote:
> 
>>>how can i add one week to clendar.time record using duration ?
>> 
>> with Ada.Calendar; use Ada.Calendar;
>> procedure One_Week
>> is
>>    One_Minute : constant Duration := 60.0;
>>    One_Hour   : constant Duration := 60 * One_Minute;
>>    One_Day    : constant Duration := 24 * One_Hour;
>>    One_Week   : constant Duration := 7 * One_Day;
>> 
>>    Now : Time := Clock;
>> begin
>>    Now := Now + One_Week;
>> end One_Week;
> 
> This may work on some implementations. If it fails, the compiler should
> issue a fatal error. In this case, Tom Moran's suggestion:
> 
>     One_Minute : constant Duration := 60.0;
>     One_Hour   : constant Duration := 60 * One_Minute;
>     One_Day    : constant Duration := 24 * One_Hour;
> 
>     Now : Time := Clock;
>     begin
>        for Day in 1 .. 7 loop
>          Now := Now + One_Day;
>        end loop;
> 
> ought to work. There is a proposal to add this functionality in the next
> revision of the language (AI-351).
> 

Will this revision include definitions based on precise
description of movements of the Earth ?  The rotation
of the Earth is not so well defined and if one wants very
high precision - as one may want within some applications
of theoretical (geo-)physics/astronomy - then I guess such
calendar definitions cannot be implemented in a computer language ?

The "Ada calender" will be more like the "official/standard calendar" -
but this is subject to frequent modifications ?

Or does there exist a stable calendar standard which everybody agree on ? 

reinert