# Tie::RefHash - man - phpman

## NAME
    [Tie::RefHash](https://www.chedong.com/phpMan.php/perldoc/Tie%3A%3ARefHash/markdown) - Use references as hash keys

## VERSION
    version 1.40

## SYNOPSIS
        require 5.004;
        use [Tie::RefHash](https://www.chedong.com/phpMan.php/perldoc/Tie%3A%3ARefHash/markdown);
        tie HASHVARIABLE, '[Tie::RefHash](https://www.chedong.com/phpMan.php/perldoc/Tie%3A%3ARefHash/markdown)', LIST;
        tie HASHVARIABLE, '[Tie::RefHash::Nestable](https://www.chedong.com/phpMan.php/perldoc/Tie%3A%3ARefHash%3A%3ANestable/markdown)', 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](https://www.chedong.com/phpMan.php/perldoc/Tie%3A%3ARefHash%3A%3ANestable/markdown), included
    as part of [Tie::RefHash](https://www.chedong.com/phpMan.php/perldoc/Tie%3A%3ARefHash/markdown).

    It is implemented using the standard perl TIEHASH interface. Please see the "tie" entry in
### perlfunc

    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](https://www.chedong.com/phpMan.php/perldoc/Tie%3A%3ARefHash/markdown);
        tie %h, '[Tie::RefHash](https://www.chedong.com/phpMan.php/perldoc/Tie%3A%3ARefHash/markdown)';
        $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](https://www.chedong.com/phpMan.php/perldoc/Tie%3A%3ARefHash%3A%3ANestable/markdown)';
        $h{$a}->{$b} = 1;
        for (keys %h, keys %{$h{$a}}) {
           print ref($_), "\n";
        }

## THREAD SUPPORT
    [Tie::RefHash](https://www.chedong.com/phpMan.php/perldoc/Tie%3A%3ARefHash/markdown) 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

## 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>>).

## AUTHORS
    Gurusamy Sarathy <<gsar@activestate.com>>

    [Tie::RefHash::Nestable](https://www.chedong.com/phpMan.php/perldoc/Tie%3A%3ARefHash%3A%3ANestable/markdown) by Ed Avis <<ed@membled.com>>

## 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.