7 Tie::RefHash - use references as hash keys
13 tie HASHVARIABLE, 'Tie::RefHash', LIST;
14 tie HASHVARIABLE, 'Tie::RefHash::Nestable', LIST;
20 This module provides the ability to use references as hash keys if you
21 first C<tie> the hash variable to this module. Normally, only the
22 keys of the tied hash itself are preserved as references; to use
23 references as keys in hashes-of-hashes, use Tie::RefHash::Nestable,
24 included as part of Tie::Hash.
26 It is implemented using the standard perl TIEHASH interface. Please
27 see the C<tie> entry in perlfunc(1) and perltie(1) for more information.
29 The Nestable version works by looking for hash references being stored
30 and converting them to tied hashes so that they too can have
31 references as keys. This will happen without warning whenever you
32 store a reference to one of your own hashes in the tied hash.
37 tie %h, 'Tie::RefHash';
43 %h = ($a => 1, $b => 2, $c => 3, $d => 4, $e => 5);
50 tie %h, 'Tie::RefHash::Nestable';
52 for (keys %h, keys %{$h{$a}}) {
58 Gurusamy Sarathy gsar@activestate.com
62 Version 1.21 22 Jun 1999
66 perl(1), perlfunc(1), perltie(1)
80 $s->STORE(shift, shift);
88 if (defined $s->[0]{"$k"}) {
103 $s->[0]{"$k"} = [$k, $v];
113 (ref $k) ? delete($s->[0]{"$k"}) : delete($s->[1]{$k});
118 (ref $k) ? exists($s->[0]{"$k"}) : exists($s->[1]{$k});
123 keys %{$s->[0]}; # reset iterator
124 keys %{$s->[1]}; # reset iterator
133 if (($k, $v) = each %{$s->[0]}) {
134 return $s->[0]{"$k"}[0];
140 return each %{$s->[1]};
150 package Tie::RefHash::Nestable;
151 use vars '@ISA'; @ISA = qw(Tie::RefHash);
155 if (ref($v) eq 'HASH' and not tied %$v) {
157 tie %$v, ref($s), @elems;
159 $s->SUPER::STORE($k, $v);