Re: Locale bikeshed time

["writeonce@midipix.org" <writeonce@midipix.org>]

On 07/23/2014 10:24 PM, Rich Felker wrote:
> On Wed, Jul 23, 2014 at 10:16:40PM -0400, writeonce@midipix.org wrote:
>>>> implementation of %E? could use weak aliases and standardized hooks,
>>>> then applications or calendar-specific libraries could provide these
>>>> hooks and still use the libc strftime, rather than a complex system
>>>> of wrappers and conditionals.
>>> That's now how weak symbols work -- they're not a way to add plug-in
>>> code.
>>>
>> Thanks for the clarification.  This leaves a query to a local
>> service the more likely solution since for at least the Hijri
>> (Muslim) and Hebrew (Jewish) calendars, accurate conversion cannot
>> be based on data or tables alone.
> How so? All code is fundamentally data/tables. Is your point that the
> current data is not sufficient to compute all future times (in which
> case updated data would be needed but sufficient) or just that the
> algorithms are moderately complex (in which case a the data would have
> to represent a nontrivial computational language).
For one thing, the algorithms for past dates are moderately (or somehow 
more than moderately) complex.  This pertains to both the Hijri and 
Hebrew calendars.  With respect to future dates, in the most traditional 
Muslim countries the first day of the month is predicted via astronomic, 
yet confirmed via traditional means (observation of the new moon).  In 
those countries you might therefore find out "in real time" whether 
tonight is the 1st of the next month, or the 30th of the current one.  
For date conversion to be accurate, then, you would have to get your 
data updated on a monthly basis, which at least for me makes a local 
service the better solution.  Obviously, things would have been much 
easier if the wise and elderly had designed their calendars with an ISO 
libc in mind (a bug in the prophet utility?), but I personally wouldn't 
dare trying to change them;-)
>   
>
> In any case this is probably quite low priority. I'm not aware of any
> other libc supporting these features or any significant demand for
> them. So it's a neat topic to discuss, but getting pretty far off
> topic from the topic at hand (locale support in 1.1.4).
>
> Rich
>
>
Of course.  That's why I suggested to define only the interfaces (or 
hooks, which now I understand are not an option), and not worry about 
the implementation.

zg