SPL RecursiveArrayIterator::offset(Un)Set has no effect on instance created with ArrayObject

Hello All,


It seems to me that an instance of RecursiveIteratorIterator with ArrayObject has no effect
when calling RecursiveArrayIterator::offsetUnset or RecursiveArrayIterator::offsetSet methods.
But everything works fine when the iterator is created with a json_decoded - json_encoded array.

I expect the same behavior of these two iterators, but maybe I am wrong.
Any guidance would be appreciated.


Test script:
----------------------------------
function example() {

    $array = array (
            'name' => 'text',
            'items'    => array (
                    '0'    => array ( 'phrase' => 'text text', ),
                    '1'    => array ( 'phrase' => 'text text text', ),
                    'ctrl' => array( '0' => '1', ),
            ),
    );

    $array_object = json_decode( json_encode( $array ));
   
 $iterator     = new RecursiveIteratorIterator( new 
RecursiveArrayIterator( $array_object ), 
RecursiveIteratorIterator::CHILD_FIRST );

    // comment these two lines and see the nice execution
    $array_object = new ArrayObject( $array, 0, "RecursiveArrayIterator"  );
    $iterator     = new RecursiveIteratorIterator( $array_object->getIterator(), RecursiveIteratorIterator::CHILD_FIRST );

    foreach( $iterator as $key => $value ) {

        $array_copy   = $iterator->getInnerIterator()->getArrayCopy();
        $keys         = array_keys( $array_copy );
        $numeric_keys = array_filter( $keys, 'is_numeric' );

        if( count( $numeric_keys ) !== 0 && count( $keys  ) == count( $numeric_keys ) + 1 ) {

            $ctrl = $array_copy['ctrl'];
            $iterator->getInnerIterator()->offsetUnset( 'ctrl' );

            foreach( $iterator->getInnerIterator() as $ctrl_value => $value ) {

                if( in_array( $ctrl_value, $ctrl )) {
                    $iterator->getInnerIterator()->getChildren()->offsetSet( 'ctrl', $ctrl_value );
                } else {
                    $iterator->getInnerIterator()->getChildren()->offsetSet( 'ctrl', '' );
                }
            }
            // print_r( $iterator->getInnerIterator() );
        }
    }
    print_r( object_to_array( $array_object ));
    // print_r( iterator_to_array( $iterator ));
}

// helper method
function object_to_array( $object ) {
    if( ! is_array( $object ) && ! is_object( $object )) {
        return $object;
    }
    if( is_object( $object )) {
        $object = get_object_vars( $object );
    }
    return array_map( __FUNCTION__, $object );
}

example();


Expected result:
--------------------------
[11-Mar-2013 18:24:48 UTC] Array
(
    [name] => text
    [items] => Array
        (
            [0] => Array
                (
                    [phrase] => text text
                    [ctrl] => 
                )

            [1] => Array
                (
                    [phrase] => text text text
                    [ctrl] => 1
                )
        )
)