public static function __set_state( array $array )
    {
        // handle old exported states
        if ( !array_key_exists( 'properties', $array ) )
        {
            return new ezcPersistentObjectProperty( $array['columnName'],
                                                    $array['propertyName'],
                                                    $array['propertyType'] );
        }
        return new ezcPersistentObjectProperty( $array['properties']['columnName'],
                                                $array['properties']['propertyName'],
                                                $array['properties']['propertyType'] );
    }