Re: Hijri calendar support in glibc

["(Imed Chihi) عماد الشيحي" <imed dot chihi at gmail dot com>]

Salam Ahmed,

2008/2/14, أحمد المحمودي <aelmahmoudy at users dot sourceforge dot net>:
>   I have been doing some research about the possibility of adding hijri
>   calendar directly into glibc.
>   I found that glibc does support other calendars, such as Buddhist Era
>   (using in Thailand, and Laos I think) and the Japanese Emperors'
>   reigns.
>
>   That is done by adding definitions for era, era_d_t_fmt, era_d_fmt,
>   era_t_fmt, and alt_digits in the locale [1].
>
>   Those definitions modify the behaviour of some time functions (such as
>   strftime) when E and O modifiers are used [2].
>
>   The format of 'era' consists of semicolon-separated strings. Each
>   string shall be an era description segment with the format:
>
>   direction:offset:start_date:end_date:era_name:era_format
>
>   The descriptions for each field are in [1].
>
>   Now the problem is that supported calendars are those which are based
>   on Gregorian calendar. In [3] it says:
>
>   The E modifier supports alternative date formats, such as the Japanese
>   Emperor's Era, as long as these are based on the Gregorian calendar
>   system. Extending the E modifiers to other date elements may provide
>   an implementation-defined extension capable of supporting other
>   calendar systems, especially in combination with the O modifier.
>
>   So, I was thinking, that this 'era' can be used for Hijri as follows:
>
>   1. For countries that formally use Hijri system, we can add an 'era'
>   definition in their respective locale files. The era field that
>   matters now is 'era_name'. It can be something like "A.H." or even
>   "ه".
>
>   2. In glibc C code: a conversion function from Gregorian to Hijri can
>   be added, I was thinking of using the conversion functions that
>   implement the Um-Ul-Qura algorithm since, as far as I know, this is
>   the algorithm that is formally used in Arabia.
>
>   3. Somewhere in glibc's time/strftime_l.c & time/strptime_l.c [4], the
>   code should check if era_name is "A.H" or "ه", if that is true, it
>   will call for the conversion function to get the appropriate Hijri
>   date.
>
>   I hope to get your comments on this suggestion.

Thank you for this impressive assessment. I have never looked into
those parts of glibc, but if we can get an example implementation,
then we will be able to request feedback from the glibc maintainers.

 -Imed

-- 
Imed Chihi - عماد الشيحي
http://perso.hexabyte.tn/ichihi/