Zefram schreef:
> I recommend Math::BigRat, which you'll have noticed I'm quite a fan of.
> Bignums mean never having to think how big your floats are.
I will take a look.
> >I don't understand why you say DT does not know about CJDNs.
>
> Did you notice that JD refers to Universal Time but CJD is
> timezone-relative? That's one of the things that Date::JD makes work
> right.
Timezone-relative day counts are not implemented by DT; that is true.
But have you looked at the DT::Format::Epoch example in my first mail yet?
Example:
# Parser object $cjd defined as in previous mail
my $dt = DateTime->now( time_zone => 'UTC' );
printf "%s %.3f %.3f\n", $dt, $dt->jd, $cjd->format_datetime( $dt );
$dt->set_time_zone( 'America/New_York' );
printf "%s %.3f %.3f\n", $dt, $dt->jd, $cjd->format_datetime( $dt );
Output:
Datetime JD CJD
======== == ===
2006-07-17T21:06:28 2453934.379 2453934.879
2006-07-17T17:06:28 2453934.379 2453934.713
> In DateTime this issue gets into the floating timezone, which
> looks like a right can of worms. I think the floating timezone is trying
> to make DateTime do too many things in one class. It's schizophrenic.
If you care about leap seconds, just stay far away from the floating
timezone.
> Looks like another abstraction inversion to me: what's a specific calendar
> doing in such a fundamental class?
The only reason DateTime.pm (the module) seems to be the fundamental
class of DateTime (the project) is the name; it has no central role,
although there are a number of modules (e.g. formatting modules) that
have been written especially for DT.pm, because it is the most commonly
used.
> How do you convert between two non-Gregorian calendars using DateTime?
Every DT::Calendar module has two required functions: one that returns
the RD and the number of elapsed seconds in the day; and one that
accepts these values and converts them to a new object.
See http://datetime.perl.org/index.cgi?CalendarModules for details.
Eugene
