public function set_id($id)
{
if (!is_array(self::$ids)) {
self::$ids = array();
}
if (is_null($id)) {
throw new Exception('The required parameter is not present: id');
}
if (in_array($id, self::$ids)) {
throw new Exception('Only one control with the id \'' . $id . '\' can be on the page');
}
self::$ids[] = $id;
$this->id = $id;
}
