DateTime::Calendar::Julian(3)              User Contributed Perl Documentation


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.

       o   calendar_name

           Returns 'Julian'.

       o   gregorian_deviation

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

       o   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://github.com/trwyant/perl-DateTime-Calendar-Julian/issues> or in
       electronic mail to harryfmudd@comcast.net.

AUTHOR
       Eugene van der Pijll <pijll@gmx.net>

       Thomas R. Wyant, III harryfmudd at comcast dot net

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

       Copyright (C) 2018-2022, 2026 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/>

perl v5.42.2                      2026-06-19     DateTime::Calendar::Julian(3)