Issue #2318281 by tim.plunkett, dawehner | kim.pepper: Provide a standard way...

Issue #2318281 by tim.plunkett, dawehner | kim.pepper: Provide a standard way to check a plugin is an instance of the required interface.

core/lib/Drupal/Component/Plugin/Factory/DefaultFactory.php

@@ -8,7 +8,6 @@
 
 use Drupal\Component\Plugin\Discovery\DiscoveryInterface;
 use Drupal\Component\Plugin\Exception\PluginException;
-use Drupal\Component\Plugin\Derivative\DeriverInterface;
 
 /**
  * Default plugin factory.
@@ -30,11 +29,24 @@ class DefaultFactory implements FactoryInterface {
    */
   protected $discovery;
 
+  /**
+   * Defines an interface each plugin should implement.
+   *
+   * @var string|null
+   */
+  protected $interface;
+
   /**
    * Constructs a Drupal\Component\Plugin\Factory\DefaultFactory object.
+   *
+   * @param \Drupal\Component\Plugin\Discovery\DiscoveryInterface $discovery
+   *   The plugin discovery.
+   * @param string|null $plugin_interface
+   *   (optional) The interface each plugin should implement.
    */
-  public function __construct(DiscoveryInterface $discovery) {
+  public function __construct(DiscoveryInterface $discovery, $plugin_interface = NULL) {
     $this->discovery = $discovery;
+    $this->interface = $plugin_interface;
   }
 
   /**
@@ -42,7 +54,7 @@ public function __construct(DiscoveryInterface $discovery) {
    */
   public function createInstance($plugin_id, array $configuration = array()) {
     $plugin_definition = $this->discovery->getDefinition($plugin_id);
-    $plugin_class = static::getPluginClass($plugin_id, $plugin_definition);
+    $plugin_class = static::getPluginClass($plugin_id, $plugin_definition, $this->interface);
     return new $plugin_class($configuration, $plugin_id, $plugin_definition);
   }
 
@@ -53,13 +65,18 @@ public function createInstance($plugin_id, array $configuration = array()) {
    *   The id of a plugin.
    * @param mixed $plugin_definition
    *   The plugin definition associated with the plugin ID.
+   * @param string $required_interface
+   *   (optional) THe required plugin interface.
    *
    * @return string
    *   The appropriate class name.
    *
    * @throws \Drupal\Component\Plugin\Exception\PluginException
+   *   Thrown when there is no class specified, the class doesn't exist, or
+   *   the class does not implement the specified required interface.
+   *
    */
-  public static function getPluginClass($plugin_id, $plugin_definition = NULL) {
+  public static function getPluginClass($plugin_id, $plugin_definition = NULL, $required_interface = NULL) {
     if (empty($plugin_definition['class'])) {
       throw new PluginException(sprintf('The plugin (%s) did not specify an instance class.', $plugin_id));
     }
@@ -70,6 +87,10 @@ public static function getPluginClass($plugin_id, $plugin_definition = NULL) {
       throw new PluginException(sprintf('Plugin (%s) instance class "%s" does not exist.', $plugin_id, $class));
     }
 
+    if ($required_interface && !is_subclass_of($plugin_definition['class'], $required_interface)) {
+      throw new PluginException(sprintf('Plugin "%s" (%s) in %s should implement interface %s.', $plugin_id, $plugin_definition['class'], $plugin_definition['provider'], $required_interface));
+    }
+
     return $class;
   }
 }

core/lib/Drupal/Component/Plugin/Factory/ReflectionFactory.php

@@ -19,7 +19,7 @@ class ReflectionFactory extends DefaultFactory {
    */
   public function createInstance($plugin_id, array $configuration = array()) {
     $plugin_definition = $this->discovery->getDefinition($plugin_id);
-    $plugin_class = static::getPluginClass($plugin_id, $plugin_definition);
+    $plugin_class = static::getPluginClass($plugin_id, $plugin_definition, $this->interface);
 
     // Lets figure out of there's a constructor for this class and pull
     // arguments from the $options array if so to populate it.

core/lib/Drupal/Core/Action/ActionManager.php

@@ -33,7 +33,7 @@ class ActionManager extends DefaultPluginManager {
    *   The module handler to invoke the alter hook with.
    */
   public function __construct(\Traversable $namespaces, CacheBackendInterface $cache_backend, ModuleHandlerInterface $module_handler) {
-    parent::__construct('Plugin/Action', $namespaces, $module_handler, 'Drupal\Core\Annotation\Action');
+    parent::__construct('Plugin/Action', $namespaces, $module_handler, 'Drupal\Core\Action\ActionInterface', 'Drupal\Core\Annotation\Action');
     $this->alterInfo('action_info');
     $this->setCacheBackend($cache_backend, 'action_info');
   }

core/lib/Drupal/Core/Archiver/ArchiverManager.php

 <?php
 
 /**
+ * @file
  * Contains \Drupal\Core\Archiver\ArchiverManager.
  */
 
@@ -32,7 +33,7 @@ class ArchiverManager extends DefaultPluginManager {
    *   The module handler to invoke the alter hook with.
    */
   public function __construct(\Traversable $namespaces, CacheBackendInterface $cache_backend, ModuleHandlerInterface $module_handler) {
-    parent::__construct('Plugin/Archiver', $namespaces, $module_handler, 'Drupal\Core\Archiver\Annotation\Archiver');
+    parent::__construct('Plugin/Archiver', $namespaces, $module_handler, 'Drupal\Core\Archiver\ArchiverInterface', 'Drupal\Core\Archiver\Annotation\Archiver');
     $this->alterInfo('archiver_info');
     $this->setCacheBackend($cache_backend, 'archiver_info_plugins');
   }
@@ -42,7 +43,7 @@ public function __construct(\Traversable $namespaces, CacheBackendInterface $cac
    */
   public function createInstance($plugin_id, array $configuration = array()) {
     $plugin_definition = $this->getDefinition($plugin_id);
-    $plugin_class = DefaultFactory::getPluginClass($plugin_id, $plugin_definition);
+    $plugin_class = DefaultFactory::getPluginClass($plugin_id, $plugin_definition, 'Drupal\Core\Archiver\ArchiverInterface');
     return new $plugin_class($configuration['filepath']);
   }
 

core/lib/Drupal/Core/Block/BlockManager.php

@@ -44,7 +44,7 @@ class BlockManager extends DefaultPluginManager implements BlockManagerInterface
    *   The module handler to invoke the alter hook with.
    */
   public function __construct(\Traversable $namespaces, CacheBackendInterface $cache_backend, ModuleHandlerInterface $module_handler) {
-    parent::__construct('Plugin/Block', $namespaces, $module_handler, 'Drupal\Core\Block\Annotation\Block');
+    parent::__construct('Plugin/Block', $namespaces, $module_handler, 'Drupal\Core\Block\BlockPluginInterface', 'Drupal\Core\Block\Annotation\Block');
 
     $this->alterInfo('block');
     $this->setCacheBackend($cache_backend, 'block_plugins');

core/lib/Drupal/Core/Condition/ConditionManager.php

@@ -42,7 +42,7 @@ public function __construct(\Traversable $namespaces, CacheBackendInterface $cac
     $this->alterInfo('condition_info');
     $this->setCacheBackend($cache_backend, 'condition_plugins');
 
-    parent::__construct('Plugin/Condition', $namespaces, $module_handler, 'Drupal\Core\Condition\Annotation\Condition');
+    parent::__construct('Plugin/Condition', $namespaces, $module_handler, 'Drupal\Core\Condition\ConditionInterface', 'Drupal\Core\Condition\Annotation\Condition');
   }
 
   /**

core/lib/Drupal/Core/Display/VariantManager.php

@@ -31,7 +31,7 @@ class VariantManager extends DefaultPluginManager {
    *   The module handler to invoke the alter hook with.
    */
   public function __construct(\Traversable $namespaces, CacheBackendInterface $cache_backend, ModuleHandlerInterface $module_handler) {
-    parent::__construct('Plugin/DisplayVariant', $namespaces, $module_handler, 'Drupal\Core\Display\Annotation\DisplayVariant');
+    parent::__construct('Plugin/DisplayVariant', $namespaces, $module_handler, 'Drupal\Core\Display\VariantInterface', 'Drupal\Core\Display\Annotation\DisplayVariant');
 
     $this->setCacheBackend($cache_backend, 'variant_plugins');
     $this->alterInfo('display_variant_plugin');

core/lib/Drupal/Core/Entity/EntityManager.php

@@ -171,7 +171,7 @@ class EntityManager extends DefaultPluginManager implements EntityManagerInterfa
    *   The class resolver.
    */
   public function __construct(\Traversable $namespaces, ModuleHandlerInterface $module_handler, CacheBackendInterface $cache, LanguageManagerInterface $language_manager, TranslationInterface $translation_manager, ClassResolverInterface $class_resolver, TypedDataManager $typed_data_manager) {
-    parent::__construct('Entity', $namespaces, $module_handler, 'Drupal\Core\Entity\Annotation\EntityType');
+    parent::__construct('Entity', $namespaces, $module_handler, 'Drupal\Core\Entity\EntityInterface', 'Drupal\Core\Entity\Annotation\EntityType');
 
     $this->setCacheBackend($cache, 'entity_type', array('entity_types' => TRUE));
     $this->alterInfo('entity_type');

core/lib/Drupal/Core/Field/FieldTypePluginManager.php

@@ -31,7 +31,7 @@ class FieldTypePluginManager extends DefaultPluginManager implements FieldTypePl
    *   The module handler.
    */
   public function __construct(\Traversable $namespaces, CacheBackendInterface $cache_backend, ModuleHandlerInterface $module_handler) {
-    parent::__construct('Plugin/Field/FieldType', $namespaces, $module_handler, 'Drupal\Core\Field\Annotation\FieldType');
+    parent::__construct('Plugin/Field/FieldType', $namespaces, $module_handler, 'Drupal\Core\Field\FieldItemInterface', 'Drupal\Core\Field\Annotation\FieldType');
     $this->alterInfo('field_info');
     $this->setCacheBackend($cache_backend, 'field_types_plugins');
   }

core/lib/Drupal/Core/Field/FormatterPluginManager.php

@@ -47,8 +47,7 @@ class FormatterPluginManager extends DefaultPluginManager {
    *   The 'field type' plugin manager.
    */
   public function __construct(\Traversable $namespaces, CacheBackendInterface $cache_backend, ModuleHandlerInterface $module_handler, FieldTypePluginManagerInterface $field_type_manager) {
-
-    parent::__construct('Plugin/Field/FieldFormatter', $namespaces, $module_handler, 'Drupal\Core\Field\Annotation\FieldFormatter');
+    parent::__construct('Plugin/Field/FieldFormatter', $namespaces, $module_handler, 'Drupal\Core\Field\FormatterInterface', 'Drupal\Core\Field\Annotation\FieldFormatter');
 
     $this->setCacheBackend($cache_backend, 'field_formatter_types_plugins');
     $this->alterInfo('field_formatter_info');

core/lib/Drupal/Core/Field/WidgetFactory.php

@@ -19,7 +19,7 @@ class WidgetFactory extends DefaultFactory {
    */
   public function createInstance($plugin_id, array $configuration = array()) {
     $plugin_definition = $this->discovery->getDefinition($plugin_id);
-    $plugin_class = static::getPluginClass($plugin_id, $plugin_definition);
+    $plugin_class = static::getPluginClass($plugin_id, $plugin_definition, $this->interface);
     return new $plugin_class($plugin_id, $plugin_definition, $configuration['field_definition'], $configuration['settings']);
   }
 }

core/lib/Drupal/Core/Field/WidgetPluginManager.php

@@ -47,7 +47,7 @@ class WidgetPluginManager extends DefaultPluginManager {
    *   The 'field type' plugin manager.
    */
   public function __construct(\Traversable $namespaces, CacheBackendInterface $cache_backend, ModuleHandlerInterface $module_handler, FieldTypePluginManagerInterface $field_type_manager) {
-    parent::__construct('Plugin/Field/FieldWidget', $namespaces, $module_handler, 'Drupal\Core\Field\Annotation\FieldWidget');
+    parent::__construct('Plugin/Field/FieldWidget', $namespaces, $module_handler, 'Drupal\Core\Field\WidgetInterface', 'Drupal\Core\Field\Annotation\FieldWidget');
 
     $this->setCacheBackend($cache_backend, 'field_widget_types_plugins');
     $this->alterInfo('field_widget_info');

core/lib/Drupal/Core/ImageToolkit/ImageToolkitManager.php

@@ -43,7 +43,7 @@ class ImageToolkitManager extends DefaultPluginManager {
    *   The config factory.
    */
   public function __construct(\Traversable $namespaces, CacheBackendInterface $cache_backend, ModuleHandlerInterface $module_handler, ConfigFactoryInterface $config_factory) {
-    parent::__construct('Plugin/ImageToolkit', $namespaces, $module_handler, 'Drupal\Core\ImageToolkit\Annotation\ImageToolkit');
+    parent::__construct('Plugin/ImageToolkit', $namespaces, $module_handler, 'Drupal\Core\ImageToolkit\ImageToolkitInterface', 'Drupal\Core\ImageToolkit\Annotation\ImageToolkit');
 
     $this->setCacheBackend($cache_backend, 'image_toolkit_plugins');
     $this->configFactory = $config_factory;

core/lib/Drupal/Core/ImageToolkit/ImageToolkitOperationManager.php

@@ -46,7 +46,7 @@ class ImageToolkitOperationManager extends DefaultPluginManager implements Image
    *   A logger instance.
    */
   public function __construct(\Traversable $namespaces, CacheBackendInterface $cache_backend, ModuleHandlerInterface $module_handler, LoggerInterface $logger) {
-    parent::__construct('Plugin/ImageToolkit/Operation', $namespaces, $module_handler, 'Drupal\Core\ImageToolkit\Annotation\ImageToolkitOperation');
+    parent::__construct('Plugin/ImageToolkit/Operation', $namespaces, $module_handler, 'Drupal\Core\ImageToolkit\ImageToolkitOperationInterface', 'Drupal\Core\ImageToolkit\Annotation\ImageToolkitOperation');
 
     $this->alterInfo('image_toolkit_operation');
     $this->setCacheBackend($cache_backend, 'image_toolkit_operation_plugins');

core/lib/Drupal/Core/Mail/MailManager.php

@@ -12,8 +12,6 @@
 use Drupal\Core\Cache\CacheBackendInterface;
 use Drupal\Core\Extension\ModuleHandlerInterface;
 use Drupal\Core\Config\ConfigFactoryInterface;
-use Drupal\Component\Utility\String;
-use Drupal\Component\Plugin\Exception\InvalidPluginDefinitionException;
 use Drupal\Core\StringTranslation\StringTranslationTrait;
 use Drupal\Core\StringTranslation\TranslationInterface;
 
@@ -67,7 +65,7 @@ class MailManager extends DefaultPluginManager implements MailManagerInterface {
    *   The string translation service.
    */
   public function __construct(\Traversable $namespaces, CacheBackendInterface $cache_backend, ModuleHandlerInterface $module_handler, ConfigFactoryInterface $config_factory, LoggerChannelFactoryInterface $logger_factory, TranslationInterface $string_translation) {
-    parent::__construct('Plugin/Mail', $namespaces, $module_handler, 'Drupal\Core\Annotation\Mail');
+    parent::__construct('Plugin/Mail', $namespaces, $module_handler, 'Drupal\Core\Mail\MailInterface', 'Drupal\Core\Annotation\Mail');
     $this->alterInfo('mail_backend_info');
     $this->setCacheBackend($cache_backend, 'mail_backend_plugins');
     $this->configFactory = $config_factory;
@@ -149,16 +147,7 @@ public function getInstance(array $options) {
     }
 
     if (empty($this->instances[$plugin_id])) {
-      $plugin = $this->createInstance($plugin_id);
-      if (is_subclass_of($plugin, '\Drupal\Core\Mail\MailInterface')) {
-        $this->instances[$plugin_id] = $plugin;
-      }
-      else {
-        throw new InvalidPluginDefinitionException($plugin_id, String::format('Class %class does not implement interface %interface', array(
-          '%class' => get_class($plugin),
-          '%interface' => 'Drupal\Core\Mail\MailInterface',
-        )));
-      }
+      $this->instances[$plugin_id] = $this->createInstance($plugin_id);
     }
     return $this->instances[$plugin_id];
   }

core/lib/Drupal/Core/Menu/ContextualLinkManager.php

@@ -105,7 +105,7 @@ class ContextualLinkManager extends DefaultPluginManager implements ContextualLi
   public function __construct(ControllerResolverInterface $controller_resolver, ModuleHandlerInterface $module_handler, CacheBackendInterface $cache_backend, LanguageManagerInterface $language_manager, AccessManagerInterface $access_manager, AccountInterface $account, RequestStack $request_stack) {
     $this->discovery = new YamlDiscovery('links.contextual', $module_handler->getModuleDirectories());
     $this->discovery = new ContainerDerivativeDiscoveryDecorator($this->discovery);
-    $this->factory = new ContainerFactory($this);
+    $this->factory = new ContainerFactory($this, '\Drupal\Core\Menu\ContextualLinkInterface');
 
     $this->controllerResolver = $controller_resolver;
     $this->accessManager = $access_manager;

core/lib/Drupal/Core/Menu/LocalActionManager.php

@@ -116,7 +116,7 @@ public function __construct(ControllerResolverInterface $controller_resolver, Re
     // discovery.
     $this->discovery = new YamlDiscovery('links.action', $module_handler->getModuleDirectories());
     $this->discovery = new ContainerDerivativeDiscoveryDecorator($this->discovery);
-    $this->factory = new ContainerFactory($this);
+    $this->factory = new ContainerFactory($this, 'Drupal\Core\Menu\LocalActionInterface');
     $this->controllerResolver = $controller_resolver;
     $this->requestStack = $request_stack;
     $this->routeProvider = $route_provider;

core/lib/Drupal/Core/Menu/LocalTaskManager.php

@@ -126,7 +126,7 @@ class LocalTaskManager extends DefaultPluginManager implements LocalTaskManagerI
   public function __construct(ControllerResolverInterface $controller_resolver, RequestStack $request_stack, RouteProviderInterface $route_provider, RouteBuilderInterface $route_builder, ModuleHandlerInterface $module_handler, CacheBackendInterface $cache, LanguageManagerInterface $language_manager, AccessManagerInterface $access_manager, AccountInterface $account) {
     $this->discovery = new YamlDiscovery('links.task', $module_handler->getModuleDirectories());
     $this->discovery = new ContainerDerivativeDiscoveryDecorator($this->discovery);
-    $this->factory = new ContainerFactory($this);
+    $this->factory = new ContainerFactory($this, '\Drupal\Core\Menu\LocalTaskInterface');
     $this->controllerResolver = $controller_resolver;
     $this->requestStack = $request_stack;
     $this->routeProvider = $route_provider;

core/lib/Drupal/Core/Plugin/DefaultPluginManager.php

@@ -9,7 +9,6 @@
 
 use Drupal\Component\Plugin\Discovery\CachedDiscoveryInterface;
 use Drupal\Component\Plugin\Discovery\DiscoveryCachedTrait;
-use Drupal\Component\Plugin\Exception\PluginNotFoundException;
 use Drupal\Core\Plugin\Discovery\ContainerDerivativeDiscoveryDecorator;
 use Drupal\Component\Plugin\PluginManagerBase;
 use Drupal\Component\Plugin\PluginManagerInterface;
@@ -17,7 +16,6 @@
 use Drupal\Core\Cache\Cache;
 use Drupal\Core\Cache\CacheBackendInterface;
 use Drupal\Core\Extension\ModuleHandlerInterface;
-use Drupal\Core\Language\LanguageManagerInterface;
 use Drupal\Core\Plugin\Discovery\AnnotatedClassDiscovery;
 use Drupal\Core\Plugin\Factory\ContainerFactory;
 
@@ -92,15 +90,17 @@ class DefaultPluginManager extends PluginManagerBase implements PluginManagerInt
    *   keyed by the corresponding namespace to look for plugin implementations.
    * @param \Drupal\Core\Extension\ModuleHandlerInterface $module_handler
    *   The module handler.
+   * @param string|null $plugin_interface
+   *   (optional) The interface each plugin should implement.
    * @param string $plugin_definition_annotation_name
    *   (optional) The name of the annotation that contains the plugin definition.
    *   Defaults to 'Drupal\Component\Annotation\Plugin'.
    */
-  public function __construct($subdir, \Traversable $namespaces, ModuleHandlerInterface $module_handler, $plugin_definition_annotation_name = 'Drupal\Component\Annotation\Plugin') {
+  public function __construct($subdir, \Traversable $namespaces, ModuleHandlerInterface $module_handler, $plugin_interface = NULL, $plugin_definition_annotation_name = 'Drupal\Component\Annotation\Plugin') {
     $this->subdir = $subdir;
     $this->discovery = new AnnotatedClassDiscovery($subdir, $namespaces, $plugin_definition_annotation_name);
     $this->discovery = new ContainerDerivativeDiscoveryDecorator($this->discovery);
-    $this->factory = new ContainerFactory($this);
+    $this->factory = new ContainerFactory($this, $plugin_interface);
     $this->moduleHandler = $module_handler;
   }
 

core/lib/Drupal/Core/Plugin/Factory/ContainerFactory.php

@@ -18,7 +18,7 @@ class ContainerFactory extends DefaultFactory {
    */
   public function createInstance($plugin_id, array $configuration = array()) {
     $plugin_definition = $this->discovery->getDefinition($plugin_id);
-    $plugin_class = static::getPluginClass($plugin_id, $plugin_definition);
+    $plugin_class = static::getPluginClass($plugin_id, $plugin_definition, $this->interface);
 
     // If the plugin provides a factory method, pass the container to it.
     if (is_subclass_of($plugin_class, 'Drupal\Core\Plugin\ContainerFactoryPluginInterface')) {