NAME

Tie::Autotie - Automatically ties underlying references

SYNOPSIS

'Tie::Module', # the module to autotie
[ 'use', 'args' ], # arguments to 'use Tie::Module'
[ 'tie', 'args' ]; # arguments to tie() for Tie::Module
# then use Tie::Module as usual

DESCRIPTION

This module allows you to automatically tie data structures contained in a tied data structure. As an example:

use Tie::Autotie 'Tie::IxHash';
tie my(%hash), 'Tie::IxHash';
$hash{jeff}{age} = 22;
$hash{jeff}{lang} = 'Perl';
$hash{jeff}{brothers} = 3;
$hash{jeff}{sisters} = 4;
$hash{kristin}{age} = 22;
$hash{kristin}{lang} = 'Latin';
$hash{kristin}{brothers} = 1;
$hash{kristin}{sisters} = 0;
for my $who (keys %hash) {
print "$who:\n";
for my $what (keys %{ $hash{$who} }) {
print " $what = $hash{$who}{$what}\n";
}
}

This program outputs:

jeff:
age = 22
lang = Perl
brothers = 3
sisters = 4
kristin:
age = 22
lang = Latin
brothers = 1
sisters = 0

You can see that the keys of %hash are returned in the order in which they were created, as well as the keys of the sub-hashes.

BUGS

  • A non-autotied layer

    It only works if each layer is being autotied. As soon as there's a layer that is not being autotied, all layers inside it will also be ignored:

    use Tie::Autotie 'Tie::IxHash';
    tie my(%hash), 'Tie::IxHash';
    $hash{a}{b} = 1; # %{ $hash{a} } is autotied
    $hash{a}{c} = 2; # so keys %{ $hash{a} } returns ('b', 'c')
    $hash{d}[0]{a}{y} = 3; # %{ $hash{d} } is autotied, but Tie::IxHash has
    $hash{d}[0]{a}{x} = 4; # no control over $hash{d}[0], so $hash{d}[0]{a}
    # is not autotied

    At the moment, there's no way to get around this. Please stick to using data structures that your tying module can handle.

  • Assigning a reference

    In the Tie::IxHash example, you cannot do:

    $hash{jeff} = {
    age => 22,
    lang => 'Perl',
    brothers => 3,
    sisters => 4,
    };

    because that creates a hash reference, not an object of Tie::IxHash. This hash reference ends up being destroyed anyway, and replaced with a Tie::IxHash object that points to an empty hash.

AUTHOR

Jeff japhy Pinyan, <japhy@pobox.com>

COPYRIGHT AND LICENSE

Copyright (C) 2004 by japhy

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself, either Perl version 5.8.3 or, at your option, any later version of Perl 5 you may have available.

1 POD Error

The following errors were encountered while parsing the POD:

Around line 139:

You forgot a '=back' before '=head1'