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Tie::RefHash - Use references as hash keys
Contents
Contributors
• Yuval Kogman <nothingmuch@woobling.org>
• Karen Etheridge <ether@cpan.org>
• Florian Ragwitz <rafl@debian.org>
• Jerry D. Hedden <jdhedden@cpan.org>
Copyright And Licence
This software is copyright (c) 2006 by יובל קוג'מן (Yuval Kogman) <nothingmuch@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 v5.40.1 2025-07-03 Tie::RefHash(3perl)
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";
}
Name
Tie::RefHash - Use references as hash keys
See Also
perl(1), perlfunc(1), perltie(1)
Storable Support
Storable hooks are provided for semantically correct serialization and cloning of tied refhashes.
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@rt.cpan.org <mailto:bug-Tie-RefHash@rt.cpan.org>).
Synopsis
require 5.004;
use Tie::RefHash;
tie HASHVARIABLE, 'Tie::RefHash', LIST;
tie HASHVARIABLE, 'Tie::RefHash::Nestable', LIST;
untie HASHVARIABLE;
Thread Support
Tie::RefHash fully supports threading using the "CLONE" method.
Version
version 1.40
PNG Icons
