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::RefHash.
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
60 'Nestable' by Ed Avis ed@membled.com
68 perl(1), perlfunc(1), perltie(1)
77 require overload; # to support objects with overloaded ""
84 $s->STORE(shift, shift);
92 my $kstr = overload::StrVal($k);
93 if (defined $s->[0]{$kstr}) {
108 $s->[0]{overload::StrVal($k)} = [$k, $v];
119 ? (delete($s->[0]{overload::StrVal($k)}) || [])->[1]
120 : delete($s->[1]{$k});
125 (ref $k) ? exists($s->[0]{overload::StrVal($k)}) : exists($s->[1]{$k});
130 keys %{$s->[0]}; # reset iterator
131 keys %{$s->[1]}; # reset iterator
132 $s->[2] = 0; # flag for iteration, see NEXTKEY
140 if (($k, $v) = each %{$s->[0]}) {
147 return each %{$s->[1]};
157 package Tie::RefHash::Nestable;
159 @ISA = 'Tie::RefHash';
163 if (ref($v) eq 'HASH' and not tied %$v) {
165 tie %$v, ref($s), @elems;
167 $s->SUPER::STORE($k, $v);