NAME
DateTime::Fiction::JRRTolkien::Shire.pm
SYNOPSIS
use DateTime::Fiction::JRRTolkien::Shire;
# Constructors
my $shire = DateTime::Fiction::JRRTolkien::Shire->new(year => 1419,
month => 'Rethe',
day => 25);
my $shire = DateTime::Fiction::JRRTolkien::Shire->new(year => 1419,
month => 3,
day => 25);
my $shire = DateTime::Fiction::JRRTolkien::Shire->new(year => 1419,
holiday => '2 Lithe');
my $shire = DateTime::Fiction::JRRTolkien::Shire->from_epoch(epoch = $time);
my $shire = DateTime::Fiction::JRRTolkien::Shire->today; # same as from_epoch(epoch = time());
my $shire = DateTime::Fiction::JRRTolkien::Shire->from_object(object => $some_other_DateTime_object);
my $shire = DateTime::Fiction::JRRTolkien::Shire->from_day_of_year(year => 1420,
day_of_year => 182);
my $shire2 = $shire->clone;
# Accessors
$year = $shire->year;
$month = $shire->month; # 1 - 12, or 0 on a holiday
$month_name = $shire->month_name;
$day = $shire->day; # 1 - 30, or 0 on a holiday
$dow = $shire->day_of_week; # 1 - 7, or 0 on certain holidays
$day_name = $shire->day_name;
$holiday = $shire->holiday;
$holiday_name = $shire->holiday_name;
$leap = $shire->is_leap_year;
$time = $shire->epoch;
@rd = $shire->utc_rd_values;
# Set Methods
$shire->set(year => 7463,
month => 5,
day => 3);
$shire->set(year => 7463,
holiday => 6);
$shire->truncate(to => 'month');
# Comparisons
$shire < $shire2;
$shire == $shire2;
# Strings
print "$shire1\n"; # Prints Sunday 25 Rethe 1419
# On this date in history
print $shire->on_date;
DESCRIPTION
Implementation of the calendar used by the hobbits in J.R.R. Tolkien's
exceptional novel The Lord of The Rings, as described in Appendix D of
that book (except where noted). The calendar has 12 months, each with 30
days, and 5 holidays that are not part of any month. A sixth holiday,
Overlithe, is added on leap years. The holiday Midyear's Day (and the
Overlithe on a leap year) is not part of any week, which means that the
year always starts on Sterday.
This module is a follow on to the Date::Tolkien::Shire module, and is
rewritten to support Dave Rolsky and company's DateTime module. The
DateTime module must be installed for this module to work. Unlike the
DateTime module, which includes time support, this calendar does not
have any mechanisms for giving a shire time (mostly because I've never
quite figured out what it should look like). Time is maintained,
however, so that objects can be converted from other calendars to the
shire calendar and then converted back without their time components
being lost. The same is true of time zones.
METHODS
Most of these methods mimic their corresponding DateTime methods in
functionality. For additional information on these methods, see the
DateTime documentation.
Constructors
* new( ... )
This method takes a year, month, and day parameter, or a year and
holiday parameter. The year can be any value. The month can be
specified with a string giving the name of the month (the same
string that would be returned by month_name, with the first letter
capitalized and the rest in lower case) or by giving the numerical
value for the month, between 1 and 12. The day should always be
between 1 and 30. If a holiday is given instead of a day and month,
it should be the name of the holiday as returned by holiday_name
(with the first letter of each word capitalized) or a value between
1 and 6. The 1 through 6 numbers map to holidays as follows: 1 => 2
Yule 2 => 1 Lithe 3 => Midyear's Day 4 => Overlithe # Leap years
only 5 => 2 Lithe 6 => 1 Yule
The new method will also take parameters for hour, minute, second,
nanosecond, time_zone and locale. If given, these parameters will be
stored in case the object is converted to another class that
supports times.
If a day is not given, it will default to 1. If neither a day or
month is given, the date will default to 2 Yule, the first day of
the year.
* from_epoch( epoch => $epoch, ... )
Same as in DateTime.
* now( ... )
Same as in DateTime. Note that this is equivalent to from_epoch(
epoch => time() );
* today( ... )
Same as in DateTime.
* from_object( object => $object, ... )
Same as in DateTime. Takes any other DateTime calendar object and
converts it to a DateTime::Fiction::JRRTolkien::Shire object.
* last_day_of_month( ... )
Same as in DateTime. Like the new constructor, but it does not take
a day parameter. Instead, the day is set to 30, which is the last
day of any month in the shire calendar. A holiday parameter should
not be used with this method. Use new instead.
* from_day_of_year( year => $year, day_of_year => $yday)
Same as in DateTime. Gets the date from the given year and day of
year, both of which must be given. Hour, minute, second, time_zone,
etc. parameters may also be given, and will be passed to the
underlying DateTime object, just like in new.
* clone
Creates a new Shire object that is the same date (and underlying
time) as the calling object.
Get Methods
* year
returns the year.
* month
Returns the month number, from 1 to 12. If the date is a holiday, a
0 is returned for the month.
* month_name
Returns the name of the month. If the date is a holiday, an empty
string is returned.
* day_of_month, day, mday
Returns the day of the current month, from 1 to 30. If the date is a
holiday, 0 is returned.
* day_of_week, wday, dow
Returns the day of the week from 1 to 7. If the day is not part of
any week (Midyear's Day or the Overlithe), 0 is returned.
* day_name
Returns the name of the day of the week, or an empty string if the
day is not part of any week.
* day_name_trad
Like day_name, but returns the more traditional name of the days of
the week, as defined in Appendix D.
* day_of year, doy
Returns the day of the year, from 1 to 366
* holiday
Returns the holiday number (given in the description of the new
constructor). If the day is not a holiday, 0 is returned.
* holiday_name
Returns the name of the holiday. If the day is not a holiday, an
empty string is returned.
* is_leap_year
Returns 1 if the year is a leap year, and 0 otherwise.
Leap years are given the same rule as the Gregorian calendar. Every
four years is a leap year, except the first year of the century,
which is not a leap year. However, every fourth century (400 years),
the first year of the century is a leap year (every 4, except every
100, except every 400). This is a slight change from the calendar
descibed in Appendix D, which uses the rule of once every 4 years,
except every 100 years (the same as in the Julian calendar). Given
some uncertainty about how many years have passed since the time in
Lord of the Rings (see note below), and the expectations of most
people that the years match up with what they're used to, I have
changed this rule for this implementation. However, this does mean
that this calendar implementation is not strictly that described in
Appendix D.
* week
A two element array, where the first is the week_year and the latter
is the week_number.
* week_year
This is always the same as the year in the shire calendar, but is
present for compatability with other DateTime objects.
* week_number
Returns the week of the year.
* epoch
Returns the epoch of the given object, just like in DateTime.
* hires_epoch
Returns the epoch as a floating point number, with the fractional
portion for fractional seconds. Functions the same as in DateTime.
* utc_rd_values
Returns the UTC rata die days, seconds, and nanoseconds. Ignores
fractional seconds. This is the standard method used by other
methods to convert the shire calendar to other calendars. See the
DateTime documentation for more information.
* utc_rd_as_seconds
Returns the UTC rata die days entirely as seconds.
* on_date
Prints out the current day. If the day has some events that
transpired on it (as defined in Appendix B of the Lord of the
Rings), those events are also printed. This can be fun to put in a
.bashrc or .cshrc. Try
perl -MDateTime::Fiction::JRRTolkien::Shire
-le 'print DateTime::Fiction::JRRTolkien::Shire->now->on_date;'
Set Methods
* Set( ... )
Allows the day, month, and year to be changed. It takes any
parameters allowed by new constructor, including all those supported
by DateTime and the holiday parameter, except for time_zone. This is
used in much the same way as new, with the exception that any
parameters not given will be left as is.
All parameters are optional, with the current values inserted if the
values are not supplied. However, with holidays not falling in any
month, it is recommended that a day and month always be given
together. Otherwise, unanticipated results may occur.
As in the new constructor, time parameters have no effect on the
shire dates returned. However, they are maintained in case the
object is converted to another calendar which supports time.
* Truncate( ... )
Same as in DateTime. If the date is a holiday, a truncation to
either 'month' or 'day' is equivalent. Otherwise, this functions as
specified in the DateTime object.
* set_time_zone( $tz )
Just like in DateTime. This method has no effect on the shire
calendar, but be stored with the date if it is ever converted to
another calendar with time support.
Comparisons and Stringification
All comparison operators should work, just as in DateTime. In
addition, all DateTime::Fiction::JRRTolkien::Shire objects will
interpolate into a string representing the date when used in a
double-quoted string.
DURATIONS AND DATE MATH
Durations and date math (other than comparisons) are not supported at
present on this module (patches are always welcome). If this is needed,
there are a couple of options. If workig with dates within epoch time,
the dates can be converted to epoch time, the math done, and then
converted back. Regardless of the dates, the shire objects can also be
converted to DateTime objects, the math done with the DateTime class,
and then the DateTime object converted back to a Shire object.
NOTE: YEAR CALCULATION
http://www.glyhweb.com/arda/f/fourthage.html references a letter sent by
Tolkien in 1958 in which he estimates approxiimately 6000 years have
passed since the War of the Ring and the end of the Third Age. (Thanks
to Danny O'Brien from sending me this link). I took this approximate as
an exact amount and calculated back 6000 years from 1958. This I set as
the start of the 4th age (1422 S.R.). Thus the fourth age begins in our
B.C 4042.
According to Appendix D of the Lord of the Rings, leap years in hobbit
calendar are every 4 years unless its the turn of the century, in which
case it's not a leap year. Our calendar (Gregorian) uses every 4 years
unless it's 100 years unless its 400 years. So, if no changes have been
made to the hobbit's calendar since the end of the third age, their
calendar would be about 15 days further behind ours now then when the
War of the Ring took place. Implementing this seemed to me to go against
Tolkien's general habit of converting dates in the novel to our
equivalents to give us a better sense of time. My thoughts, at least
right now, is that it is truer to the spirit of things for years to line
up, and for Midyear's day to still be approximately on the summer
solstice. So instead, I have modified Tolkien's description of the
hobbit calendar so that leap years occur once every 4 years unless it's
100 years unless it's 400 years, so as it matches the Gregorian calendar
in that regard. These 100 and 400 year intervals occur at different
times in the two calendars, so there is not a one to one correspondence
of days regardless of years. However, the variations follow a 400 year
cycle.
AUTHOR
Tom Braun <tbraun@pobox.com>
LICENSE AND COPYRIGHT
Copyright (c) 2003 Tom Braun. All rights reserved. This program is free
software; you can redistribute it and/or modify it under the same terms
as Perl itself.
The calendar implemented on this module was created by J.R.R. Tolkien,
and the copyright is still held by his estate. The license and copyright
given herein applies only to this code and not to the calendar itself.
The full text of the license can be found in the LICENSE file included
with this module.
SUPPORT
Support on this module may be obtained by emailing me. However, I am not
a developer on the other classes in the DateTime project. For support on
them, please see the support options in the DateTime documentation.
BIBLIOGRAPHY
Tolkien, J. R. R. <i>Return of the King<i>. New York: Houghton Mifflin
Press, 1955.
http://www.glyphweb.com/arda/f/fourthage.html
SEE ALSO
The DateTime project documentation (perldoc DateTime, datetime@perl.org
mailing list, or http://datetime.perl.org/).