Nette\Utils\ObjectMixin::setExtensionMethod PHP Method

    public static function setExtensionMethod($class, $name, $callback)
    {
        $name = strtolower($name);
        self::$extMethods[$name][$class] = Callback::check($callback);
        self::$extMethods[$name][''] = NULL;
    }

 public static function registerControls()
 {
     ObjectMixin::setExtensionMethod(Container::class, 'addDatePicker', function (Container $container, $name, $label = null) {
         return $container[$name] = new Controls\DatePicker($label);
     });
     ObjectMixin::setExtensionMethod(Container::class, 'addDateTimePicker', function (Container $container, $name, $label = null) {
         return $container[$name] = new Controls\DateTimePicker($label);
     });
     ObjectMixin::setExtensionMethod(Container::class, 'addTypeahead', function (Container $container, $name, $label = null, $callback = null) {
         return $container[$name] = new Controls\Typeahead($label, $callback);
     });
 }