plucky (3) DateTime::Calendar::Julian.3pm.gz

NAME

       DateTime::Calendar::Julian - Dates in the Julian calendar

SYNOPSIS

         use DateTime::Calendar::Julian;

         $dt = DateTime::Calendar::Julian->new( year  => 964,
                                                month => 10,
                                                day   => 16,
                                              );

         # convert Julian->Gregorian...

         $dtgreg = DateTime->from_object( object => $dt );
         print $dtgreg->datetime;  # prints '0964-10-21T00:00:00'

         # ... and back again

         $dtjul = DateTime::Calendar::Julian->from_object( object => $dtgreg );
         print $dtjul->datetime;  # prints '0964-10-16J00:00:00'

DESCRIPTION

       DateTime::Calendar::Julian implements the Julian Calendar.  This module implements all methods of
       DateTime; see the DateTime(3) manpage for all methods.

METHODS

       This module implements one additional method besides the ones from DateTime, and changes the output of
       one other method.

       •   calendar_name

           Returns 'Julian'.

       •   gregorian_deviation

           Returns the difference in days between the Gregorian and the Julian calendar.

       •   datetime

             print $dt->datetime( $sep ), "\n";

           This method is equivalent to

             join $sep, $dt->ymd( '-' ), $dt->hms( ':' );

           The $sep argument defaults to 'J'.

           Caveat: the optional argument was added to this method in version 1.02, to belatedly track a change
           made in DateTime version 1.43 released 2017-05-29. Fixing this restores the original stringification
           behavior of this class, which was to return an ISO-8601 string unless a formatter was set. Before
           this change, the stringification separated date and time with either a 'T' or a 'J', depending on
           which version of DateTime was installed.

       Note that as of version "0.106_01", methods related to quarters should work.

BACKGROUND

       The Julian calendar was introduced by Julius Caesar in 46BC.  It featured a twelve-month year of 365
       days, with a leap year in February every fourth year.  This calendar was adopted by the Christian church
       in 325AD.  Around 532AD, Dionysius Exiguus moved the starting point of the Julian calendar to the
       calculated moment of birth of Jesus Christ. Apart from differing opinions about the start of the year
       (often January 1st, but also Christmas, Easter, March 25th and other dates), this calendar remained
       unchanged until the calendar reform of pope Gregory XIII in 1582.  Some backward countries, however, used
       the Julian calendar until the 18th century or later.

       This module uses the proleptic Julian calendar for years before 532AD, or even 46BC.  This means that
       dates are calculated as if this calendar had existed unchanged from the beginning of time.  The
       assumption is made that January 1st is the first day of the year.

       Note that BC years are given as negative numbers, with 0 denoting the year 1BC (there was no year 0AD!),
       -1 the year 2BC, etc.

SUPPORT

       Support for this module is provided via the datetime@perl.org email list. See <https://lists.perl.org/>
       for more details.

       Please report bugs to <https://rt.cpan.org/Public/Dist/Display.html?Name=DateTime-Calendar-Julian>,
       <https://github.com/trwyant/perl-DateTime-Calendar-Julian/issues>, or in electronic mail to
       wyant@cpan.org.

AUTHOR

       Eugene van der Pijll <pijll@gmx.net>

       Thomas R. Wyant, III wyant at cpan dot org

COPYRIGHT AND LICENSE

       Copyright (c) 2003 Eugene van der Pijll.  All rights reserved.

       Copyright (C) 2018-2022 Thomas R. Wyant, III

       This program is free software; you can redistribute it and/or modify it under the same terms as Perl
       itself.

       This program is distributed in the hope that it will be useful, but without any warranty; without even
       the implied warranty of merchantability or fitness for a particular purpose.

SEE ALSO

       DateTime

       DateTime::Calendar::Christian

       datetime@perl.org mailing list

       <http://datetime.perl.org/>