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package List::Rotation::Cycle; |
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use vars qw( $VERSION ); |
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$VERSION = 1.009; |
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use strict; |
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use warnings; |
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use Memoize; |
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memoize('new'); |
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sub new { |
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my $class = shift; |
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do { |
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require Carp; |
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Carp::croak ("Incorrect number of arguments; must be >= 1."); |
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} unless @_ >= 1; |
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my $self = [ @_ ]; |
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my $closure = sub { |
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push @$self, shift @$self; |
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return $self->[-1]; |
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}; |
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bless $closure, $class; |
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} |
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sub next { |
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my $self = shift; |
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&{ $self }; |
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} |
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"List::Rotation::Cycle"; |
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__END__ |
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=head1 NAME |
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List::Rotation::Cycle - Cycle through a list of values via a singleton object implemented as closure. |
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=head1 SYNOPSIS |
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use List::Rotation::Cycle; |
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my @array = qw( A B C ); |
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my $first_cycle = List::Rotation::Cycle->new(@array); |
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my $second_cycle = List::Rotation::Cycle->new(@array); |
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print $first_cycle->next; ## prints A |
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print $second_cycle->next; ## prints B |
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print $first_cycle->next; ## prints C |
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print $second_cycle->next; ## prints A, looping back to beginning |
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=head1 DESCRIPTION |
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Use C<List::Rotation::Cycle> to loop through a list of values. |
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Once you get to the end of the list, you go back to the beginning. |
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C<List::Rotation::Cycle> is implemented as a Singleton Pattern. You always just |
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get 1 (the very same) Cycle object even if you use the new method several times. |
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This is done by using C<Memoize> on the C<new> method. It returns the same object |
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for every use of C<new> that comes with the same List of parameters. |
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=head1 OBJECT METHODS |
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69
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=over 4 |
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71
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=item new |
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73
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Create a Cycle object for the list of values in the list. |
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75
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=item next |
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Return the next element. This method is implemented as a closure. |
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79
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=back |
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81
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=head1 AUTHOR |
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83
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Imre Saling, C<< <pelagicatcpandotorg> >> |
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=head1 COPYRIGHT and LICENSE |
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87
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Copyright 2000-2004, Imre Saling, All rights reserved. |
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89
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This software is available under the same terms as perl. |
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=cut |