DateTime::Event::RecurUsereContributed Perl DocuDateTime::Event::Recurrence(3)NAMEDateTime::Event::Recurrence - DateTime::Set extension for create basic
recurrence sets
SYNOPSIS
use DateTime;
use DateTime::Event::Recurrence;
my $dt = DateTime->new( year => 2000,
month => 6,
day => 20,
);
my $daily_set = DateTime::Event::Recurrence->daily;
my $dt_next = $daily_set->next( $dt );
my $dt_previous = $daily_set->previous( $dt );
my $bool = $daily_set->contains( $dt );
my @days = $daily_set->as_list( start => $dt1, end => $dt2 );
my $iter = $daily_set->iterator;
while ( my $dt = $iter->next ) {
print ' ', $dt->datetime;
}
DESCRIPTION
This module provides convenience methods that let you easily create
"DateTime::Set" objects for various recurrences, such as "once a month"
or "every day". You can also create more complicated recurrences, such
as "every Monday, Wednesday and Thursday at 10:00 AM and 2:00 PM".
USAGE
ยท yearly monthly weekly daily hourly minutely secondly
These methods all return a new "DateTime::Set" object representing
the given recurrence.
my $daily_set = DateTime::Event::Recurrence->daily;
If no parameters are given, then the set members each occur at the
beginning of the specified recurrence.
For example, by default, the "monthly()" method returns a set
containing the first day of each month.
Without parameters, the "weekly()" method returns a set containing
Mondays.
However, you can pass in parameters to alter where these datetimes
fall. The parameters are the same as those given to the
"DateTime::Duration" constructor for specifying the length of a
duration. For example, to create a set representing a daily
recurrence at 10:30 each day, we write this:
my $daily_at_10_30_set =
DateTime::Event::Recurrence->daily( hours => 10, minutes => 30 );
To represent every Tuesday (second day of the week):
my $weekly_on_tuesday_set =
DateTime::Event::Recurrence->weekly( days => 2 );
A negative duration counts backwards from the end of the period.
This is done in the same manner as is specified in RFC 2445 (iCal).
Negative durations are useful for creating recurrences such as the
last day of each month:
my $last_day_of_month_set =
DateTime::Event::Recurrence->monthly( days => -1 );
You can also provide multiple sets of duration arguments, such as
this:
my $set = DateTime::Event::Recurrence->daily
( hours => [ 10, 14, -1 ],
minutes => [ 15, 30, -15 ],
);
This specifies a recurrence occurring every day at these 9
different times:
10:15, 10:30, 10:45, # +10h ( +15min / +30min / last 15min (-15) )
14:15, 14:30, 14:45, # +14h ( +15min / +30min / last 15min (-15) )
23:15, 23:30, 23:45, # last 1h (-1) ( +15min / +30min / last 15min (-15) )
To create a set of recurrences occurring every thirty seconds, we
could do this:
my $every_30_seconds_set =
DateTime::Event::Recurrence->minutely( seconds => [ 0, 30 ] );
The following is also valid. See the section on the "interval"
parameter:
my $every_30_seconds_set =
DateTime::Event::Recurrence->secondly( interval => 30 );
Invalid DateTimes
Invalid values are skipped at run time.
For example, when days are added to a month, the result is checked for
a nonexisting day (such as 31 or 30), and the invalid datetimes are
skipped.
Another example of this would be creating a set via the "daily()"
method and specifying "hours => 25".
The "days" Parameter
The "days" parameter can be combined with yearly, monthly, and weekly
recurrences, resulting in six possible meanings:
# tuesday of every week
my $set = DateTime::Event::Recurrence->weekly( days => 2 );
# 10th day of every month
my $set = DateTime::Event::Recurrence->monthly( days => 10 );
# second tuesday of every month
my $set = DateTime::Event::Recurrence->monthly( weeks => 2, days => 2 );
# 10th day of every year
my $set = DateTime::Event::Recurrence->yearly( days => 10 );
# 10th day of every december
my $set = DateTime::Event::Recurrence->yearly( months => 12, days => 10 );
# second tuesday of every year
my $set = DateTime::Event::Recurrence->yearly( weeks => 2, days => 2 );
Week days can also be called by name, as is specified in RFC 2445
(iCal):
my $weekly_on_tuesday_set =
DateTime::Event::Recurrence->weekly( days => 'tu' );
The "days" parameter defaults to "the first day". See also the section
on the "week start day" parameter.
# second monday of every month
my $set = DateTime::Event::Recurrence->monthly( weeks => 2 );
The "interval" and "start" Parameters
The "interval" parameter represents how often the recurrence rule
repeats.
The optional "start" parameter specifies where to start counting:
my $dt_start = DateTime->new( year => 2003, month => 6, day => 15 );
my $set = DateTime::Event::Recurrence->daily
( interval => 11,
hours => 10,
minutes => 30,
start => $dt_start,
);
This specifies a recurrence that happens at 10:30 on the day specified
by "start => $dt", and then every 11 days before and after $dt. So we
get a set like this:
...
2003-06-04T10:30:00,
2003-06-15T10:30:00,
2003-06-26T10:30:00,
...
In this case, the method is used to specify the unit, so "daily()"
means that our unit is a day, and "interval => 11" specifies the
quantity of our unit.
The "start" parameter should have no time zone.
The "week_start_day" Parameter
The "week_start_day" parameter is intended for internal use by the
"DateTime::Event::ICal" module, for generating RFC2445 recurrences.
The "week_start_day" represents how the 'first week' of a period is
calculated:
"mo" - this is the default. The first week is one that starts in
monday, and has the most days in this period.
"tu", "we", "th", "fr", "sa", "su" - The first week is one that starts
in this week-day, and has the most days in this period. Works for
"weekly" and "yearly" recurrences.
"1tu", "1we", "1th", "1fr", "1sa", "1su" - The first week is one that
starts in this week-day, and has all days in this period. This works
for "weekly()", "monthly()" and "yearly()" recurrences.
Time Zones
Recurrences are created in the 'floating' time zone, as specified in
the "DateTime" module.
If you want to specify a time zone for a recurrence, you can do this by
calling "set_time_zone()" on the returned set:
my $daily = DateTime::Event::Recurrence->daily;
$daily->set_time_zone( 'Europe/Berlin' );
You can also pass a "DateTime.pm" object with a time zone to the set's
"next()" and "previous()" methods:
my $dt = DateTime->today( time_zone => 'Europe/Berlin' );
my $next = $daily->next($dt);
A recurrence can be affected DST changes, so it would be possible to
specify a recurrence that creates nonexistent datetimes. Because
"DateTime.pm" throws an exception if asked to create a non-existent
datetime, please be careful when setting a time zone for your
recurrence.
It might be preferable to always use "UTC" for your sets, and then
convert the returned object to the desired time zone.
Leap Seconds
There are no leap seconds, because the recurrences are created in the
'floating' time zone.
The value 60 for seconds (the leap second) is ignored. If you really
want the leap second, then specify the second as "-1".
AUTHOR
Flavio Soibelmann Glock fglock@pucrs.br
CREDITS
The API was developed with help from the people in the
datetime@perl.org list.
Special thanks to Dave Rolsky, Ron Hill and Matt Sisk for being around
with ideas.
If you can understand what this module does by reading the docs, you
should thank Dave Rolsky. If you can't understand it, yell at him. He
also helped removing weird idioms from the code.
Jerrad Pierce came with the idea to move "interval" from
DateTime::Event::ICal to here.
COPYRIGHT
Copyright (c) 2003 Flavio Soibelmann Glock. All rights reserved. This
program is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.
The full text of the license can be found in the LICENSE file included
with this module.
SEE ALSO
datetime@perl.org mailing list
DateTime Web page at http://datetime.perl.org/
DateTime - date and time :)
DateTime::Set - for recurrence-set accessors docs. You can use
DateTime::Set to specify recurrences using callback subroutines.
DateTime::Event::ICal - if you need more complex recurrences.
DateTime::SpanSet - sets of intervals, including recurring sets of
intervals.
perl v5.14.1 2005-05-12 DateTime::Event::Recurrence(3)
