How to get the relationship between two custom post types into my theme?

I looked into plugin source and I found a sample that solved my problem.

I just changed a little bit.

<?php
//function.php
function get_artists_related($postid){
$artists_relation = rpt_get_object_relation($postid, ‘artistas’);
if(!empty($artists_relation)) {

$args = array(
‘post_type’ => ‘artistas’,
‘post_status’ => ‘publish’,
‘posts_per_page’ => -1,
‘post__in’ => $artists_relation
);

$results_artists = query_posts($args);

foreach ( $results_artists as $post ) {
$artistas .= ‘‘.$post->post_title.’‘ ;
}
return $artistas;
}
}

?>

<?php echo get_artists_related($post->ID); ?>