interface ActorLookup { public function getActor( int $actorId, int $queryFlags = 0 ): UserIdentity; // throw if actor is not known (fall back to master?) public function getActorByName( string $name, int $queryFlags = 0 ): ?UserIdentity; // return null if unknown public function getActorByUserId( int $userId, int $queryFlags = 0 ): ?UserIdentity;; // return null if unknown }
In addition, we may want convenience methods of getting system users, such as the "Unknown user". Not much different from getActorByName, but can have aggressive caching, and should make sure that an actor ID is always assigned.