Method setup

/**
 * Method to attach a Form object to the field.
 *
 * @param   \SimpleXMLElement  $element  The SimpleXMLElement object representing the `<field>` tag for the form field object.
 * @param   mixed              $value    The form field value to validate.
 * @param   string             $group    The field name group control value. This acts as as an array container for the field.
 *                                       For example if the field has name="foo" and the group value is set to "bar" then the
 *                                       full field name would end up being "bar[foo]".
 *
 * @return  boolean  True on success.
 *
 * @since  4.0.0
 */
public function setup(\SimpleXMLElement $element, $value, $group = null)
{
    $success = parent::setup($element, $value, $group);
    if ($success) {
        if (\strlen($element['extension'])) {
            $this->extension = (string) $element['extension'];
        } else {
            $this->extension = Factory::getApplication()->input->getCmd('extension');
        }
        if (\strlen($element['hide_all'])) {
            $this->hideAll = (string) $element['hide_all'] === 'true' || (string) $element['hide_all'] === 'yes';
        }
    }
    return $success;
}