EDIT

<?php

abstract class ItemComposeHandler {

  abstract public function getClassAttributes($item);

  abstract public function composeItem($item);

  /**

   * @param $cdm_entity

   * A CDM native entity. In case of DTOs the cdm entity can be substituted by

   * TypedEntityReference

   *

   * @return string

   */

  protected function classAttributes($cdm_entity) {

    return html_class_attribute_ref($cdm_entity);

  }

}