#!/usr/bin/perl
#
use strict;
use XML::Twig;
#my $twig=XML::Twig->new(pretty_print => 'indented', keep_encoding => 1);
my $twig=XML::Twig->new(pretty_print => 'indented');
$twig->parse( '<?xml version="1.0" encoding="UTF-8"?><myxml/>'); 
my $root= $twig->root;  
$root->set_att( 'fille' => 'clémence');
open(PF, "> out.xml") or die "can't open file $!\n";
$twig->print(\*PF);

##</code><code>##

cat out.xml                                                    
<?xml version="1.0" encoding="UTF-8"?>
<myxml fille="clémence"/