#!/usr/bin/perl

use strict;
use warnings;

use XML::Twig;

my $xml = do { local $/; <DATA>; };

my %data = (
  name => 'Billy',
  age => 12,
);

my $t = XML::Twig->new(
  twig_handlers => {
    name => sub { $_->set_text( $data{name} ); },
    age => sub { $_->set_text( $data{age} ); },
  },
  pretty_print => 'indented',
);

$t->parse( $xml );
$t->flush;

__DATA__
<?xml version="1.0" ?>
<root>
  <name>THIS CHANGES</name>
  <static>blah blah blah</static>
  <static>blah blah blah</static>
  <age>THIS CHANGES</age>
</root>