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Tie::RefHash(3perl)    Perl Programmers Reference Guide    Tie::RefHash(3perl)

NAME
       Tie::RefHash - Use references as hash keys

VERSION
       version 1.40

SYNOPSIS
           require 5.004;
           use Tie::RefHash;
           tie HASHVARIABLE, 'Tie::RefHash', LIST;
           tie HASHVARIABLE, 'Tie::RefHash::Nestable', LIST;

           untie HASHVARIABLE;

DESCRIPTION
       This module provides the ability to use references as hash keys if you
       first "tie" the hash variable to this module.  Normally, only the keys
       of the tied hash itself are preserved as references; to use references
       as keys in hashes-of-hashes, use Tie::RefHash::Nestable, included as
       part of Tie::RefHash.

       It is implemented using the standard perl TIEHASH interface.  Please
       see the "tie" entry in perlfunc(1) and perltie(1) for more information.

       The Nestable version works by looking for hash references being stored
       and converting them to tied hashes so that they too can have references
       as keys.  This will happen without warning whenever you store a
       reference to one of your own hashes in the tied hash.

EXAMPLE
           use Tie::RefHash;
           tie %h, 'Tie::RefHash';
           $a = [];
           $b = {};
           $c = \*main;
           $d = \"gunk";
           $e = sub { 'foo' };
           %h = ($a => 1, $b => 2, $c => 3, $d => 4, $e => 5);
           $a->[0] = 'foo';
           $b->{foo} = 'bar';
           for (keys %h) {
              print ref($_), "\n";
           }

           tie %h, 'Tie::RefHash::Nestable';
           $h{$a}->{$b} = 1;
           for (keys %h, keys %{$h{$a}}) {
              print ref($_), "\n";
           }

THREAD SUPPORT
       Tie::RefHash fully supports threading using the "CLONE" method.

STORABLE SUPPORT
       Storable hooks are provided for semantically correct serialization and
       cloning of tied refhashes.

SEE ALSO
       perl(1), perlfunc(1), perltie(1)

SUPPORT
       Bugs may be submitted through the RT bug tracker
       <https://rt.cpan.org/Public/Dist/Display.html?Name=Tie-RefHash> (or
       bug-Tie-RefHash AT rt.org <mailto:bug-Tie-RefHash AT rt.org>).

AUTHORS
       Gurusamy Sarathy <gsar AT activestate.com>

       Tie::RefHash::Nestable by Ed Avis <ed AT membled.com>

CONTRIBUTORS
       o   Yuval Kogman <nothingmuch AT woobling.org>

       o   Karen Etheridge <ether AT cpan.org>

       o   Florian Ragwitz <rafl AT debian.org>

       o   Jerry D. Hedden <jdhedden AT cpan.org>

COPYRIGHT AND LICENCE
       This software is copyright (c) 2006 by  ' (Yuval Kogman)
       <nothingmuch AT woobling.org>.

       This is free software; you can redistribute it and/or modify it under
       the same terms as the Perl 5 programming language system itself.

perl v5.34.0                      2025-07-25               Tie::RefHash(3perl)