Nette\Forms\Controls\BaseControl::extensionMethod PHP Method

    public static function extensionMethod($name, $callback = NULL)
    {
        if (strpos($name, '::') !== FALSE) {
            // back compatibility
            list(, $name) = explode('::', $name);
        }
        Nette\Utils\ObjectMixin::setExtensionMethod(get_called_class(), $name, $callback);
    }

 static function register()
 {
     BaseControl::extensionMethod('addDataFlag', function (BaseControl $that, $name) {
         $that->getControlPrototype()->addAttributes(['data-' . $name => TRUE]);
         return $that;
     });
     BaseControl::extensionMethod('hasDataFlag', function (BaseControl $that, $name) {
         return isset($that->getControlPrototype()->attrs['data-' . $name]);
     });
     BaseControl::extensionMethod('removeDataFlag', function (BaseControl $that, $name) {
         unset($that->getControlPrototype()->attrs['data-' . $name]);
         return $that;
     });
 }