package My::Taglib;
use strict;
use warnings;

use base qw(XML::Filter::Foo); # name of filter yet to be decided.

sub new {
    my $class = shift;
    my $self = bless ({}, $class);
    
    $self->register_ns(qw(http://www.iordy.com/ns/node));
    $self->register_tags(qw(node hello));
}

sub tag_node { 
    # gets access to all children may do some processing based on them 
    # and then add in <foo:hello /> below <title>foo</title>
}

sub tag_hello { # replaces <foo:hello /> with <hello>world</hello> }

1;
__DATA__
<data>
    <foo:node xmlns:foo="http://www.iordy.com/ns/foo">
        <title>foo</title>
    </foo:node>
</data>