public function register() {
		if ( ! $this->use_subscribe_links() ) {
			return;
		}

		foreach ( $this->default_feeds as $feed_class ) {
			// Register as a singleton for internal ease of use.
			$this->container->singleton( $feed_class, $feed_class, [ 'hook' ] );
		}

		$this->container->singleton( static::class, $this );

		$this->register_hooks();
	}