baleen / migrations

     */

    public function add($element)

    {

        if (!$element instanceof VersionInterface) {

            throw new InvalidArgumentException(sprintf(

                'Invalid type "%s". Can only add instances of "%s" to this collection.',

                VersionInterface::class,

                is_object($element) ? get_class($element) : gettype($element)

            ));

        }

        if ($this->validate($element)) {

            parent::add($element);

    public function __construct(array $resolvers, $cacheEnabled = true)

    {

        foreach ($resolvers as $resolver) {

            if (!is_object($resolver) || !$resolver instanceof ResolverInterface) {

                throw new InvalidArgumentException(sprintf(

                    'Invalid resolver of type "%s". Expected instance of "%s".',

                    is_object($resolver) ? get_class($resolver) : gettype($resolver),

                    ResolverInterface::class

                ));

            }

        }

        $this->resolvers = $resolvers;

        parent::__construct($cacheEnabled);