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