SystemConfigFormBase.php

<?php

/**
 * @file
 * Contains \Drupal\system\SystemConfigFormBase.
 */
namespace Drupal\system;

use Drupal\Core\Form\FormInterface;
use Drupal\Core\Controller\ControllerInterface;
use Drupal\Core\Config\ConfigFactory;
use Drupal\Core\Config\Context\ContextInterface;
use Symfony\Component\DependencyInjection\ContainerInterface;

/**
 * Base class for implementing system configuration forms.
 */
abstract class SystemConfigFormBase implements FormInterface, ControllerInterface {

  /**
   * Stores the configuration factory.
   *
   * @var \Drupal\Core\Config\ConfigFactory
   */
  protected $configFactory;

  /**
   * Constructs a \Drupal\system\SystemConfigFormBase object.
   *
   * @param \Drupal\Core\Config\ConfigFactory $config_factory
   *   The factory for configuration objects.
   * @param \Drupal\Core\Config\Context\ContextInterface $context
   *   The configuration context to use.
   */
  public function __construct(ConfigFactory $config_factory, ContextInterface $context) {
    $this->configFactory = $config_factory;
    $this->configFactory
      ->enterContext($context);
  }

  /**
   * {@inheritdoc}
   */
  public static function create(ContainerInterface $container) {
    return new static($container
      ->get('config.factory'), $container
      ->get('config.context.free'));
  }

  /**
   * Implements \Drupal\Core\Form\FormInterface::buildForm().
   */
  public function buildForm(array $form, array &$form_state) {
    $form['actions']['#type'] = 'actions';
    $form['actions']['submit'] = array(
      '#type' => 'submit',
      '#value' => t('Save configuration'),
      '#button_type' => 'primary',
    );

    // By default, render the form using theme_system_config_form().
    $form['#theme'] = 'system_config_form';
    return $form;
  }

  /**
   * Implements \Drupal\Core\Form\FormInterface::validateForm().
   */
  public function validateForm(array &$form, array &$form_state) {
  }

  /**
   * Implements \Drupal\Core\Form\FormInterface::submitForm().
   */
  public function submitForm(array &$form, array &$form_state) {
    drupal_set_message(t('The configuration options have been saved.'));
  }

}