"Inherit Selected Template" in Revolution?

<?php
//remove this line before pasting
/**
 * ChildTemplate plugin
 *
 * Sets a new doc's template based on the ChildTemplate TV setting of the nearest
 * ancestor. Set the default value of the ChildTemplate TV to @INHERIT
 *
 * Author: Bob Ray
 *
 * Connect to OnDocFormSave (*not* OnBeforeDocFormSave)
 *
 * looks up the tree for an ancestor that has a ChildTemplate TV setting and,
 * if found, sets it as the template. Uses the nearest ancestor with a setting
 * for that TV.
 *
 * Note: can be used with InheritParentTemplate as long as
 * InheritParentTemplate executes first (set the plugin priority on the System
 * Events tab of the plugin.).
 *
 * The TV setting, (if any) will override the InheritParentTemplate setting.
 * The ChildTemplate TV can contain the name or id of the template, but using
 * the ID will be faster.
 *
 *
 */


/* Only act on new documents -- remove this line if you want to be
* able to change the TV value and have the template updated when
* you edit and save existing resources */
if ($mode != modSystemEvent::MODE_NEW) return;

/* Get parent ID */
$parentId = $resource->get('parent');

/* Get the TV object */
$tvObj = $modx->getObject('modTemplateVar', array('name' => 'ChildTemplate'));

/* Act only if there is a parent ID (i.e., doc is not at the root) and the TV object exists */

if (tvObj) {
 
    /* Get value of TV for parent */
        if ($parentId) {

            /* Get the TV's value for that ancestor */
            $tv = $tvObj->getValue($parentId);

            if ($tv) {
                /* $tv is set -- use it for current resource's template value */
                if (is_numeric($tv)) {
                    /* It's a number -- user it */
                    $resource->set('template', $tv);
                } else {
                    /* It's a template name -- get the ID */
                    $t = $modx->getObject('modTemplate', array('templateName' => $tv));
                    if ($t) {
                        $resource->set('template', $t->get('id'));
                    }
                }
                $resource->save();
             }

        }
}