Set::Infinite::_recurrence(3pm) 			User Contributed Perl Documentation			   Set::Infinite::_recurrence(3pm)

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

       o   _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' occurence.

	   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 ), "
";
	       # sample recurrence -5,-4,-3,-2,-1,0,1,2,3,4,5

	       {
		   my $x = 234.567;
		   print "next occurence after $x = ",
			 $recurrence->{param}[0]->( $x ), "
";  # 235
		   print "previous occurence before $x = ",
			 $recurrence->{param}[2]->( $x ), "
";  # 234
	       }

	       {
		   my $x = 234;
		   print "next occurence after $x = ",
			 $recurrence->{param}[0]->( $x ), "
";  # 235
		   print "previous occurence before $x = ",
			 $recurrence->{param}[2]->( $x ), "
";  # 233
	       }

       o   is_forever

	   Returns true if the set is a single span, ranging from -Infinity to Infinity.

       o   _is_recurrence

	   Returns true if the set is an unbounded recurrence, ranging from -Infinity to Infinity.

CONSTANTS

       o   INFINITY

	   The "Infinity" value.

       o   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>.

perl v5.12.4							    2011-08-22					   Set::Infinite::_recurrence(3pm)