Yii relations managment (with new throught option)

yii_relations_managment.php

public function relations()
{
    return array(
        'roles'=>array(self::HAS_MANY,'Role','group_id'),
        'users'=>array(self::HAS_MANY,'User',array('user_id'=>'id'),'through'=>'roles'),
        'comments'=>array(self::HAS_MANY,'Comment',array('id'=>'user_id'),'through'=>'users'),
    );
}