'', 'author' => '' ), $atts ) ); if (empty($author)) { return "No author has been configured. Please use the format [author_track author=\"Robin Hobb\" amazon_id=\"pushpig-20\"]"; } else { return "Don't miss out! Get notified when ".$author." publishes a new book by clicking here!"; } } add_shortcode( 'author_track', 'pushpig_author_track_link' ); ?>