Objects implementing ArrayAccess do not support the increment/decrement operators ++ and --, unlike array() and ArrayObject()
<?php
class MyArray implements ArrayAccess
{
// offsetSet, offsetGet etc implemented
}
$x = new MyArray() ;
$x[0] = 0 ;
$x[0]++ ; //error 'Indirect modification of overloaded element has no effect'
$x[0] += 1 ; // this works OK.
?>