1Tie::RefHash(3pm)      Perl Programmers Reference Guide      Tie::RefHash(3pm)
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NAME

6       Tie::RefHash - use references as hash keys
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SYNOPSIS

9           require 5.004;
10           use Tie::RefHash;
11           tie HASHVARIABLE, 'Tie::RefHash', LIST;
12           tie HASHVARIABLE, 'Tie::RefHash::Nestable', LIST;
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14           untie HASHVARIABLE;
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DESCRIPTION

17       This module provides the ability to use references as hash keys if you
18       first "tie" the hash variable to this module.  Normally, only the keys
19       of the tied hash itself are preserved as references; to use references
20       as keys in hashes-of-hashes, use Tie::RefHash::Nestable, included as
21       part of Tie::RefHash.
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23       It is implemented using the standard perl TIEHASH interface.  Please
24       see the "tie" entry in perlfunc(1) and perltie(1) for more information.
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26       The Nestable version works by looking for hash references being stored
27       and converting them to tied hashes so that they too can have references
28       as keys.  This will happen without warning whenever you store a refer‐
29       ence to one of your own hashes in the tied hash.
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EXAMPLE

32           use Tie::RefHash;
33           tie %h, 'Tie::RefHash';
34           $a = [];
35           $b = {};
36           $c = \*main;
37           $d = \"gunk";
38           $e = sub { 'foo' };
39           %h = ($a => 1, $b => 2, $c => 3, $d => 4, $e => 5);
40           $a->[0] = 'foo';
41           $b->{foo} = 'bar';
42           for (keys %h) {
43              print ref($_), "\n";
44           }
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46           tie %h, 'Tie::RefHash::Nestable';
47           $h{$a}->{$b} = 1;
48           for (keys %h, keys %{$h{$a}}) {
49              print ref($_), "\n";
50           }
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AUTHOR

53       Gurusamy Sarathy        gsar@activestate.com
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55       'Nestable' by Ed Avis   ed@membled.com
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VERSION

58       Version 1.32
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SEE ALSO

61       perl(1), perlfunc(1), perltie(1)
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65perl v5.8.8                       2001-09-21                 Tie::RefHash(3pm)
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