--TEST-- SplFixedArray properties is compatible with ArrayObject --FILE-- exchangeArray($fixedArray); $ao[0] = new stdClass(); var_dump($ao); ?> --EXPECT-- object(ArrayObject)#1 (1) { ["storage":"ArrayObject":private]=> object(SplFixedArray)#2 (2) { [0]=> object(SplDoublyLinkedList)#3 (2) { ["flags":"SplDoublyLinkedList":private]=> int(0) ["dllist":"SplDoublyLinkedList":private]=> array(0) { } } ["0"]=> object(stdClass)#4 (0) { } } }