Implements the magic __toString() method.
public function __toString() {
$return = '';
foreach ($this->storage as $name => $value) {
if (!$value
->printed()) {
$rendered = is_object($value) ? $value
->render() : check_plain($name) . ' = "' . check_plain($value) . '"';
if ($rendered) {
$return .= " {$rendered}";
}
}
}
return $return;
}