[pdf-devel] Re: Calendar spans

[jemarch]

   > Maybe I dont understand the issue, but the calculation of the lenght
   > of months is deterministic: you only need to determine if the year of
   > the time object is a leap one.
   > 
   > Or I missing something?
   > 

   Yes, the number of days in a month can be easily computed. But which 
   would be the result of the following situation?

Hm, now I see the problem.

I think that a simple precedence rule could be used: first years are
added, then months, then days, ...

   /* Setting epoch as January 31st 2007 */
   pdf_time_from_string(my_time,
                         "2007-01-31T00:00:00+00:00",
                         PDF_TIME_FORMAT_ISO_8601);

   /* Setting calendar span as +1 month +1 year */
   cal_span.sign = 0; /* add */
   cal_span.years = 1;
   cal_span.months = 1;
   cal_span.days = 0;
   cal_span.hours = 0;
   cal_span.minutes = 0;
   cal_span.seconds = 0;

   /* Add calendar span to time object */
   pdf_time_add_cal_span(my_time, cal_span);

   /* Now... which should be the resulting date in my_time?
     * Hint: 2008 is also leap year :-) */

   The problem is that the result cannot be February 31st. So which
   would be the resulting epoch?

Using the precedence rule first we add 1 year to 2007-01-31 resulting
in 2008-01-31. Then we add 1 month (February in a leap year) resulting
in 2008-02-29.

What do you think?

-- 
Jose E. Marchesi  <address@hidden>
                  <address@hidden>

GNU Spain         http://es.gnu.org
GNU Project       http://www.gnu.org