cforge-2.0.x-dev/modules/cforge_address/src/Element/Neighbourhood.php

<?php

namespace Drupal\cforge_address\Element;

use Drupal\Core\Form\FormStateInterface;
use Drupal\Core\Render\Element\Select;

/**
 * Tweaks the default address form element
 *
 * @FormElement("cf_neighbourhood_select")
 */
class Neighbourhood extends Select {

  /**
   * {@inheritDoc}
   */
  public function getInfo() {
    $info = parent::getInfo();
    $info['#required'] = TRUE;
    return $info;
  }

  /**
   * {@inheritDoc}
   */
  public static function processSelect(&$element, FormStateInterface $form_state, &$complete_form) {
    $element['#options'] = cforge_list_neighbourhoods();
    if (!empty($element['#exclude'])) {
      $element['#options'] = array_diff($element['#options'], $element['#exclude']);
    }
    if (!isset($element['#default_value'])) {
      $element['#empty_value'] = '';
    }
    unset($element['#size']);
    return parent::processSelect($element, $form_state, $complete_form);
  }


}