I have a class implementing ArrayAccess and I'm trying to get it to work with a multidimensional array. exists and get work. set and unset are giving me a problem though.

class ArrayTest implements ArrayAccess {
    private $_arr = array(
        'test' => array(
            'bar' => 1,
            'baz' => 2
        )
    );

    public function offsetExists($name) {
        return isset($this->_arr[$name]);
    }

    public function offsetSet($name, $value) {
        $this->_arr[$name] = $value;
    }

    public function offsetGet($name) {
        return $this->_arr[$name];
    }

    public function offsetUnset($name) {
        unset($this->_arr[$name]);
    }
}

$arrTest = new ArrayTest();


isset($arrTest['test']['bar']);  // Returns TRUE

echo $arrTest['test']['baz'];    // Echo's 2

unset($arrTest['test']['bar'];   // Error
$arrTest['test']['bar'] = 5;     // Error

I know $_arr could just be made public so you could access it directly, but for my implementation it's not desired and is private.

The last 2 lines throw an error: Notice: Indirect modification of overloaded element.

I know ArrayAccess just generally doesn't work with multidimensional arrays, but is there anyway around this or any somewhat clean implementation that will allow the desired functionality?

The best idea I could come up with is using a character as a separator and testing for it in set and unset and acting accordingly. Though this gets really ugly really fast if you're dealing with a variable depth.

Does anyone know why exists and get work so as to maybe copy over the functionality?

Thanks for any help anyone can offer.