SourceManager.php

<?php

namespace Drupal\tmgmt;

use Drupal\Core\Cache\CacheBackendInterface;
use Drupal\Core\Extension\ModuleHandlerInterface;
use Drupal\Core\Plugin\DefaultPluginManager;

/**
 * A plugin manager for source plugins.
 */
class SourceManager extends DefaultPluginManager {

  /**
   * Array of instantiated source UI instances.
   *
   * @var array
   */
  protected $ui = array();
  protected $defaults = array(
    'ui' => '\\Drupal\\tmgmt\\SourcePluginUiBase',
  );

  /**
   * Constructs a ConditionManager object.
   *
   * @param \Traversable $namespaces
   *   An object that implements \Traversable which contains the root paths
   *   keyed by the corresponding namespace to look for plugin implementations.
   * @param \Drupal\Core\Cache\CacheBackendInterface $cache_backend
   *   Cache backend instance to use.
   * @param \Drupal\Core\Extension\ModuleHandlerInterface $module_handler
   *   The module handler to invoke the alter hook with.
   */
  public function __construct(\Traversable $namespaces, CacheBackendInterface $cache_backend, ModuleHandlerInterface $module_handler) {
    parent::__construct('Plugin/tmgmt/Source', $namespaces, $module_handler, 'Drupal\\tmgmt\\SourcePluginInterface', 'Drupal\\tmgmt\\Annotation\\SourcePlugin');
    $this
      ->alterInfo('tmgmt_source_plugin_info');
    $this
      ->setCacheBackend($cache_backend, 'tmgmt_source_plugin');
  }

  /**
   * Returns a source plugin UI instance.
   *
   * @param string $plugin
   *   Name of the source plugin.
   *
   * @return \Drupal\tmgmt\SourcePluginUiInterface
   *   Instance a source plugin UI instance.
   */
  public function createUIInstance($plugin) {
    if (!isset($this->ui[$plugin])) {
      $definition = $this
        ->getDefinition($plugin);
      $class = $definition['ui'];
      $this->ui[$plugin] = new $class(array(), $plugin, $definition);
    }
    return $this->ui[$plugin];
  }

}