Re: [HC Evolution] Introduction

[Ali Abdin <aliabdin aucegypt edu>]

Thanks for those URLs. I'll digest the information soon. The way that Emacs
does Islamic calendar support is weird. It is an approximation at best. And
a strange approximation. I saw one Islamic Lunar Calendar site that
basically what Emacs does, does not make sense. Emacs code is also an
approximation. Like I said - you can never code a 100% accurate Islamic
Calendar because an Islamic Scholar might just change it on you becuase the
moon was not sighted :) (luckily it can only shift two days per year).

The way emacs does it is classify the months as 'leap months' and 'non-leap
months'. Even though there is no such thing in the Islamic calendar. It
then sets the number of days or each of these months or something like
that. I don't recall the exact code, and i don't have Linux (and won't
until some gracious person can send me one). I do not believe that emacs is
the right way to go, because it makes the assumption that its Islamic
Calendar is non-changing, but it does change.

Again, I will read the URLS provided :) (I mail'd this before reading the
URLs). I do not have the calendar-book and I doubt i will find it at my
Uni's library. Naturally if somebody wishes to donate the book for me to
explore i don't mind. Otherwise i will use the postscript files JWZ
provided :)


> Ali Abdin wrote:
> > It would be very hard (impossible) to design a GUI over two functions
> > (time_t -> native and native->time_t) so you would need some sort of
(xml?)
> > file that defines the months, the number of days in months, the number
of
> > months, etc etc. But Russel Steinthal convinced me this is not really
> > necessary :)
>
> Perhaps you guys are all over this, but anyone who is thinking about
> supporting non-Gregorian calendars should have completely absorbed
> everything that Ed Reingold has written on the subject.  A web site
> about his book is here:
> http://emr.cs.uiuc.edu/home/reingold/calendar-book/
>
> A predecessor to that book is online, and is incredibly informative:
> http://emr.cs.uiuc.edu/~reingold/calendar.ps
> http://emr.cs.uiuc.edu/~reingold/calendar2.ps
> http://emr.cs.uiuc.edu/~reingold/calendars.shtml
>
> He wrote the Emacs calendar package, and it supports lots and lots of
> different calendars in a sane way.  And -- bonus points -- it's already
> GPLed, so you can cut and paste to your heart's content.  (I imagine it
> would be trivial to port it to another language; he's done it several
> times, including Java, but seems to have licensed these other ports
> under a "non-commercial use only" license.)
>
> --
> Jamie Zawinski
> jwz jwz org             http://www.jwz.org/
> jwz dnalounge com       http://www.dnalounge.com/