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.\" ========================================================================
.\"
.IX Title "Tie::RefHash 3perl"
.TH Tie::RefHash 3perl "2021-09-24" "perl v5.32.1" "Perl Programmers Reference Guide"
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.SH "NAME"
Tie::RefHash \- use references as hash keys
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 4
\&    require 5.004;
\&    use Tie::RefHash;
\&    tie HASHVARIABLE, \*(AqTie::RefHash\*(Aq, LIST;
\&    tie HASHVARIABLE, \*(AqTie::RefHash::Nestable\*(Aq, LIST;
\&
\&    untie HASHVARIABLE;
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
This module provides the ability to use references as hash keys if you
first \f(CW\*(C`tie\*(C'\fR 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.
.PP
It is implemented using the standard perl \s-1TIEHASH\s0 interface.  Please
see the \f(CW\*(C`tie\*(C'\fR entry in \fBperlfunc\fR\|(1) and \fBperltie\fR\|(1) for more information.
.PP
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.
.SH "EXAMPLE"
.IX Header "EXAMPLE"
.Vb 10
\&    use Tie::RefHash;
\&    tie %h, \*(AqTie::RefHash\*(Aq;
\&    $a = [];
\&    $b = {};
\&    $c = \e*main;
\&    $d = \e"gunk";
\&    $e = sub { \*(Aqfoo\*(Aq };
\&    %h = ($a => 1, $b => 2, $c => 3, $d => 4, $e => 5);
\&    $a\->[0] = \*(Aqfoo\*(Aq;
\&    $b\->{foo} = \*(Aqbar\*(Aq;
\&    for (keys %h) {
\&       print ref($_), "\en";
\&    }
\&
\&    tie %h, \*(AqTie::RefHash::Nestable\*(Aq;
\&    $h{$a}\->{$b} = 1;
\&    for (keys %h, keys %{$h{$a}}) {
\&       print ref($_), "\en";
\&    }
.Ve
.SH "THREAD SUPPORT"
.IX Header "THREAD SUPPORT"
Tie::RefHash fully supports threading using the \f(CW\*(C`CLONE\*(C'\fR method.
.SH "STORABLE SUPPORT"
.IX Header "STORABLE SUPPORT"
Storable hooks are provided for semantically correct serialization and
cloning of tied refhashes.
.SH "RELIC SUPPORT"
.IX Header "RELIC SUPPORT"
This version of Tie::RefHash seems to no longer work with 5.004. This has not
been throughly investigated. Patches welcome ;\-)
.SH "LICENSE"
.IX Header "LICENSE"
This program is free software; you can redistribute it and/or modify it under
the same terms as Perl itself
.SH "MAINTAINER"
.IX Header "MAINTAINER"
Yuval Kogman <nothingmuch@woobling.org>
.SH "AUTHOR"
.IX Header "AUTHOR"
Gurusamy Sarathy        gsar@activestate.com
.PP
\&'Nestable' by Ed Avis   ed@membled.com
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fBperl\fR\|(1), \fBperlfunc\fR\|(1), \fBperltie\fR\|(1)