use strict;
use warnings;
use XML::TreeBuilder;

my $xml = <<XML;
<?xml version='1.0' encoding='UTF-8'?>
<list name="name list">
        <person>
                <firstname>Paul</firstname>
                <lastname>Rutter</lastname>
                <age>24</age>
        </person>
        <person>
                        <firstname>Ruth</firstname>
                        <lastname>Brewster</lastname>
                        <age>22</age>
        </person>
        <person>
                        <firstname>Cas</firstname>
                        <lastname>Creer</lastname>
                        <age>23</age>
        </person>
</list>
XML

my $root = XML::TreeBuilder->new ();

$root->parse ($xml);

my @firstNames = map {$_->as_text ()} $root->look_down (_tag => 'firstname');

print "TreeBuilder: @firstNames\n";

use XML::Twig;

my $twig = XML::Twig->new (twig_roots   => { 'person/firstname' => \&pushName});

@firstNames = ();
$twig->parse ($xml);

print "Twig: @firstNames\n";


sub pushName {
    my ($t, $elt) = @_;
    push @firstNames, $elt->text ();
}