Plugin attributes and hooks

Drupal 11 declares plugins with PHP attributes. You put the attribute on a class in the matching src/Plugin/... directory, and the plugin manager discovers it. Annotations (the @Block-style docblocks) are the legacy form, still supported but no longer written for new code. The plugins concept page explains the system; this page is the lookup.

Example

namespace Drupal\event_rsvp\Plugin\Block;

use Drupal\Core\Block\Attribute\Block;
use Drupal\Core\Block\BlockBase;
use Drupal\Core\StringTranslation\TranslatableMarkup;

#[Block(
  id: 'event_rsvp_count',
  admin_label: new TranslatableMarkup('RSVP count'),
)]
final class RsvpCountBlock extends BlockBase {
  // ...
}

Common plugin attributes

Attribute	Declares	Plugin directory
\Drupal\Core\Block\Attribute\Block	A block	src/Plugin/Block
\Drupal\Core\Field\Attribute\FieldType	A field type	src/Plugin/Field/FieldType
\Drupal\Core\Field\Attribute\FieldWidget	A field widget	src/Plugin/Field/FieldWidget
\Drupal\Core\Field\Attribute\FieldFormatter	A field formatter	src/Plugin/Field/FieldFormatter
\Drupal\Core\Action\Attribute\Action	An action	src/Plugin/Action
\Drupal\Core\Condition\Attribute\Condition	A condition	src/Plugin/Condition
\Drupal\Core\Queue\Attribute\QueueWorker	A queue worker	src/Plugin/QueueWorker
\Drupal\Core\Layout\Attribute\Layout	A layout	src/Plugin/Layout
\Drupal\Core\Mail\Attribute\Mail	A mail backend	src/Plugin/Mail
\Drupal\Core\Validation\Attribute\Constraint	A validation constraint	src/Plugin/Validation/Constraint

Entity types are declared the same way, with \Drupal\Core\Entity\Attribute\ContentEntityType or ConfigEntityType on the entity class. Custom entity types covers them.

Views handlers each have an attribute under \Drupal\views\Attribute\ (ViewsField, ViewsFilter, ViewsArgument, ViewsStyle, and the rest), one per handler type, in the matching src/Plugin/views/<type> directory.

Annotations (legacy)

Every attribute above has an annotation predecessor in an Annotation namespace (for example \Drupal\Core\Block\Annotation\Block). You will meet them in older contrib, but each annotated plugin triggers a deprecation notice, and annotation discovery is removed in Drupal 13. Write attributes for new code, and convert annotations when you touch a file. The @Translation annotation wrapper has no attribute equivalent: in attributes, pass new TranslatableMarkup('...') directly.

OOP hooks

Hooks are implemented as methods marked with the Hook attribute, instead of procedural hook_*() functions. Hooks and events explains how to write them; convert procedural hooks to classes covers migrating existing code.

Attribute	Purpose
\Drupal\Core\Hook\Attribute\Hook	Marks a method as a hook implementation: #[Hook('form_alter')].
\Drupal\Core\Hook\Attribute\RemoveHook	Removes another module’s hook implementation.
\Drupal\Core\Hook\Attribute\ReorderHook	Reorders another module’s hook implementation.
\Drupal\Core\Hook\Attribute\LegacyHook	Marks a procedural stub that Drupal 11.1 and later skip because a class implementation exists.
\Drupal\Core\Hook\Attribute\LegacyModuleImplementsAlter	Marks a hook_module_implements_alter() that Drupal 11.2 and later skip in favor of attribute ordering.
\Drupal\Core\Hook\Attribute\ProceduralHookScanStop	Placed on a function in a .module file; Drupal stops scanning the file for procedural hooks after that function.

Order an implementation with the order argument:

Value	Effect
\Drupal\Core\Hook\Order\Order::First / Order::Last	Run before or after all others.
\Drupal\Core\Hook\Order\OrderBefore / OrderAfter	Run relative to a named module’s implementation.

Related

• Plugins for how discovery and managers work.
• Hooks and events for implementing hooks as methods.
• Convert procedural hooks to classes for migrating existing code.
• The plugin API topic on api.drupal.org.