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List-Cycle-1.04
River stage one • 3 direct dependents • 7 total dependents
/ List::Cycle

NAME

List::Cycle - Objects for cycling through a list of values

VERSION

Version 1.04

SYNOPSIS

List::Cycle gives you an iterator object for cycling through a series of values. The canonical use is for cycling through a list of colors for alternating bands of color on a report.


            

              
              
use List::Cycle;
my $colors = List::Cycle->new( {values => ['#000000', '#FAFAFA', '#BADDAD']} );
print $colors->next; # #000000
print $colors->next; # #FAFAFA
print $colors->next; # #BADDAD
print $colors->next; # #000000
print $colors->next; # #FAFAFA
... etc ...

You'd call it at the top of a loop:


            

              
              
while ( ... ) {
    my $color = $colors->next;
    print qq{<tr bgcolor="$color">;
    ...
}

Note that a List::Cycle object is not a standard Perl blessed hash. It's an inside-out object, as suggested in Perl Best Practices. In the seven years since PBP has come out, inside-out objects have been almost universally ignored, but I keep List::Cycle as an example. If you don't care about the internals of the object, then List::Cycle is a fine module for you to use.

FUNCTIONS

new( {values => \@values} )

Creates a new cycle object, using @values.

The values keyword can be vals, if you like.

$cycle->set_values(\@values)

Sets the cycle values and resets the internal pointer.

$cycle->reset

Sets the internal pointer back to the beginning of the cycle.


            

              
              
my $color = List::Cycle->new( {values => [qw(red white blue)]} );
print $color->next; # red
print $color->next; # white
$color->reset;
print $color->next; # red, not blue

$cycle->dump

Returns a handy string representation of internals.

$cycle->next

Gives the next value in the sequence.

AUTHOR

Andy Lester, <andy at petdance.com>

SUPPORT

You can find documentation for this module with the perldoc command.


            

              
              
perldoc List::Cycle

You can also look for information at:

BUGS

Please report any bugs or feature requests at https://github.com/petdance/list-cycle/issues.

ACKNOWLEDGEMENTS

List::Cycle is a playground that uses some of the ideas in Damian Conway's marvelous Perl Best Practices. http://www.oreilly.com/catalog/perlbp/ One of the chapters mentions a mythical List::Cycle module, so I made it real.

Thanks also to Ricardo SIGNES and Todd Rinaldo for patches.

COPYRIGHT & LICENSE

Copyright 2005-2012 Andy Lester.

This program is free software; you can redistribute it and/or modify it under the terms of the Artistic License v2.0.