#!/bin/perl -w
use strict;
use XML::Twig;

my $twig= XML::Twig->new(pretty_print=>'indented');

$twig->parse(\*DATA);
my $root=$twig->root;


$twig->root->first_child->sort_children( sub { $_->{'att'}->{"type"}});
$twig->root->first_child->first_child->sort_children( sub { $_->text});
#$twig->root->sort_children_on_att("type");
#$twig->root->sort_children_on_field('mainterm');

$twig->print;
__DATA__
<enhancement>
<descriptorgroup>
<descriptors type="MED" controlled="y">
<descriptor>
<mainterm weight="a">plague</mainterm>
<mainterm>disease</mainterm>
<mainterm>pestilence</mainterm>
</descriptor>
</descriptors>
<descriptors type="DRG" controlled="y">
<mainterm>panadol</mainterm>
<mainterm weight="a">zorro</mainterm>
<mainterm>xenon</mainterm>
<mainterm weight="a">aspirin</mainterm>
</descriptors>
</descriptorgroup>
</enhancement>