NAME
Set::Infinite::_recurrence - Extends Set::Infinite with recurrence functions
SYNOPSIS
$recurrence = $base_set->_recurrence ( \&next, \&previous );
DESCRIPTION
This is an internal class used by the DateTime::Set module. The API is subject to change.
It provides all functionality provided by Set::Infinite, plus the ability to define recurrences with arbitrary objects, such as dates.
METHODS
_recurrence ( \&next, \&previous )
Creates a recurrence set. The set is defined inside a 'base set'.
$recurrence = $base_set->_recurrence ( \&next, \&previous );
The recurrence functions take one argument, and return the 'next' or the 'previous' occurrence.
Example: defines the set of all 'integer numbers':
use strict; use Set::Infinite::_recurrence; use POSIX qw(floor); # define the recurrence span my $forever = Set::Infinite::_recurrence->new( Set::Infinite::_recurrence::NEG_INFINITY, Set::Infinite::_recurrence::INFINITY ); my $recurrence = $forever->_recurrence( sub { # next floor( $_[0] + 1 ) }, sub { # previous my $tmp = floor( $_[0] ); $tmp < $_[0] ? $tmp : $_[0] - 1 }, ); print "sample recurrence ", $recurrence->intersection( -5, 5 ), "\n"; # sample recurrence -5,-4,-3,-2,-1,0,1,2,3,4,5 { my $x = 234.567; print "next occurrence after $x = ", $recurrence->{param}[0]->( $x ), "\n"; # 235 print "previous occurrence before $x = ", $recurrence->{param}[2]->( $x ), "\n"; # 234 } { my $x = 234; print "next occurrence after $x = ", $recurrence->{param}[0]->( $x ), "\n"; # 235 print "previous occurrence before $x = ", $recurrence->{param}[2]->( $x ), "\n"; # 233 }
is_forever
Returns true if the set is a single span, ranging from -Infinity to Infinity.
_is_recurrence
Returns true if the set is an unbounded recurrence, ranging from -Infinity to Infinity.
CONSTANTS
INFINITY
The
Infinity
value.NEG_INFINITY
The
-Infinity
value.
SUPPORT
Support is offered through the datetime@perl.org
mailing list.
Please report bugs using rt.cpan.org
AUTHOR
Flavio Soibelmann Glock <fglock@gmail.com>
The recurrence generation algorithm is based on an idea from Dave Rolsky.
COPYRIGHT
Copyright (c) 2003 Flavio Soibelmann Glock. All rights reserved. This program is free software; you can distribute 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
Set::Infinite
DateTime::Set
For details on the Perl DateTime Suite project please see http://datetime.perl.org.