SlimPHP optional path params

slim1.php

/*@var $controllers Array of String */

/**
 * Set up Slim listeners for each controller
 */
foreach($controllers as $C){
  
    // Map GET
    $slim->get("/$C/:id(/:relation)",function($id,$relation=null){
            print_r(array(
                'id' => $id,
                'relation' => $relation
            ));
        });

    
};