MirOS Manual: Tie::RefHash(3p)

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


     Tie::RefHash - use references as hash keys


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

         untie HASHVARIABLE;


     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.


         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";


     Gurusamy Sarathy        gsar@activestate.com

perl v5.8.8                2005-02-05                           1

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

     'Nestable' by Ed Avis   ed@membled.com


     Version 1.32


     perl(1), perlfunc(1), perltie(1)

perl v5.8.8                2005-02-05                           2

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