protected function getTableClasses()
  {
    $classes = "";

    if($this->table_striped)
    {
      $classes.= "table-striped ";
    }
    if($this->table_bordered)
    {
      $classes.= "table-bordered ";
    }
    if($this->table_hover)
    {
      $classes.= "table-hover ";
    }
    if($this->table_condensed)
    {
      $classes.= "table-condensed ";
    }

    $classes.= $this->getTableExtraClassesString();

    return $classes;
  }