NAME

Date::ICal - Perl extension for ICalendar date objects.

SYNOPSIS

use Date::ICal;

$ical = Date::ICal->new( ical => '19971024T120000' );
$ical = Date::ICal->new( epoch => time );
$ical = Date::ICal->new( year => 1964,
    month => 10, day => 16, hour => 16,
    min => 12, sec => 47, tz => '0530' );

$hour = $ical->hour;
$year = $ical->year;

$ical_string = $ical->ical;
$epoch_time = $ical->epoch;

DESCRIPTION

Date::ICal talks the ICal date format, and is intended to be a base class for other date/calendar modules that know about ICal time format also.

See http://dates.rcbowen.com/unified.txt for details

METHODS

Date::ICal has the following methods available:

new

A new Date::ICal object can be created with any valid ICal string:

my $ical = Date::ICal->new( ical => '19971024T120000' );

Or with any epoch time:

my $ical = Date::ICal->new( epoch => time );

Or, better still, create it with components

my $date = Date::ICal->new( 
                       day => 25, 
                       month => 10, 
                       year => 1066,
                       hour => 7,
                       min => 15,
                       sec => 47
                       );

If you call new without any arguments, you'll get a Date::ICal object that is set to the time right now.

my $ical = Date::ICal->new();

If you already have an object in Date::ICal, or some other subclass thereof, you can create a new Date::ICal (or subclass) object using that object to start with. This is particularly useful for converting from one calendar to another:

# Direct conversion from Discordian to ISO dates
my $disco = Date::Discordian->new( disco => '12 Chaos, YOLD 3177' );
my $iso = Date::ISO->new( $disco );
print $iso->iso;

ical

$ical_string = $ical->ical;

Retrieves, or sets, the date on the object, using any valid ICal date/time string.

epoch

$epoch_time = $ical->epoch;

$ical->epoch( 98687431 );

Sets, or retrieves, the epoch time represented by the object, if it is representable as such. (Dates before 1971 or after 2038 will not have an epoch representation.)

Internals note: The ICal representation of the date is considered the only authoritative one. This means that we may need to reconstruct the epoch time from the ICal representation if we are not sure that they are in synch. We'll need to do clever things to keep track of when the two may not be in synch. And, of course, the same will go for any subclasses of this class.

add

$date->add( %hash ); # Hash of day, hour, min, etc, values
$date->add( ical => $ical_duration_string );

Adds a duration to a Date::ICal object.

Duration should be passed in as either an ical string, or as a hash of date/time properties.

The result will be normalized. That is, the output time will have meaningful values, rather than being 48:73 pm on the 34th of hexadecember.

$self->add( month=>2 );
$self->add( duration =>'P1W' );

compare

$cmp = $date1->compare($date2);

@dates = sort {$a->compare($b)} @dates;

Compare two Date::ICal objects. Semantics are compatible with sort; returns -1 if $a < $b, 0 if $a == $b, 1 if $a > $b.

day

my $day = $date->day;

Returns the day of the month.

Day is in the range 1..31

month

my $month = $date->month;

Returns the month of the year.

Month is returned as a number in the range 1..12

year

my $year = $date->year;

Returns the year.

hour

my $hour = $date->hour

Returns the hour of the day.

Hour is in the range 0..23

min

my $min = $date->min;

Returns the minute.

Minute is in the range 0..59

sec

my $sec = $date->sec;

Returns the second.

Second is in the range 0..60. The value of 60 is (maybe) needed for leap seconds. But I'm not sure if we're going to go there.

julian

my $jd = $date->jd;

Returns a listref, containing two elements. The date as a julian day, and the time as the number of seconds since midnight. This should not be thought of as a real julian day, because it's not. The module is internally consistent, and that's enough.

This really should be considered an internal method.

See the file INTERNALS for more information about this internal format.

TODO

- add timezone support, including moving between timezones

- add gmtime and localtime methods, perhaps?

- Find a solution to the 1-second round-off errors. Perhaps move to two values (date and time) rather than one single value. This change can be made internally without affecting anything outside.

INTERNALS

Please see the file INTERNALS for discussion on the internals.

AUTHOR

Rich Bowen (DrBacchus) rbowen@rcbowen.com

And the rest of the Reefknot team.

SEE ALSO

datetime@perl.org mailing list

http://reefknot.org/

http://dates.rcbowen.com/

Time::Local

Net::ICal

# CVS History #{{{

CVS History

$Log: ICal.pm,v $
Revision 1.31  2001/08/07 02:41:11  rbowen
Test::More gets angry if there are no tests.

Revision 1.30  2001/08/07 02:30:01  rbowen
Moved the inline tests into t/ for the sake of making the module more
readable. Please don't let this discorage you from writing inline
tests.

Revision 1.29  2001/08/06 19:32:39  rbowen
Creating an object without args was calling gmtime( $args{epoch} ).
Fixed and added tests. Also added Time::HiRes to PREREQ list.

Revision 1.28  2001/08/06 18:45:47  rbowen
sub epoch was referencing another sub that has gone away. Fixed, and
added tests.

Revision 1.27  2001/08/02 04:38:16  srl
Adjusted the add() method to return a copy of $self instead of the
return value of $self->jd(). This was important to making
the Net::ICal tests pass, but it's also the Right Way, I think.

Revision 1.26  2001/08/02 03:47:59  rbowen
Handle negative durations correctly.

Revision 1.25  2001/08/01 02:19:03  rbowen
Two main changes here.
1) Split the internal date/time representation into date, time
integers, so that we don't have any more roundoff error.
2) Memoized the parsetime and parsedate methods, so that we're not
doing that three times every time we want three components, which we
were doing.

#}}}

cpanm Date::ICal

perl -MCPAN -e shell
install Date::ICal