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Tie::Cycle(3) User Contributed Perl Documentation Tie::Cycle(3)


Tie::Cycle - Cycle through a list of values via a scalar.


        use v5.10;
        use Tie::Cycle;
        tie my $cycle, 'Tie::Cycle', [ qw( FFFFFF 000000 FFFF00 ) ];
        say $cycle; # FFFFFF
        say $cycle; # 000000
        say $cycle; # FFFF00
        say $cycle; # FFFFFF  back to the beginning
        (tied $cycle)->reset;  # back to the beginning


You use "Tie::Cycle" to go through a list over and over again. Once you get to the end of the list, you go back to the beginning. You don't have to worry about any of this since the magic of tie does that for you.

The tie takes an array reference as its third argument. The tie should succeed unless the argument is not an array reference. Previous versions required you to use an array that had more than one element (what's the pointing of looping otherwise?), but I've removed that restriction since the number of elements you want to use may change depending on the situation.

During the tie, this module makes a shallow copy of the array reference. If the array reference contains references, and those references are changed after the tie, the elements of the cycle will change as well. See the included script for an example of this effect.


You can call methods on the underlying object (which you access with tied() ).

Roll the iterator back to the starting position. The next access will give the first element in the list.
Give the previous element. This does not affect the current position.
Give the next element. This does not affect the current position. You can peek at the next element if you like.


This module is on Github:


brian d foy, "<>"


Copyright © 2000-2024, brian d foy "<>". All rights reserved. This software is available under the Artistic License 2.0.

2024-03-08 perl v5.40.0