<?phpclass MyClass extends RecursiveIteratorIterator{ public function __construct() { parent::__construct(new MyClass_Letters); }}class MyClass_Letters extends RecursiveArrayIterator{ public function __construct() { parent::__construct(array('a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z')); } public function hasChildren() { return true; } public function getChildren() { return new MyClass_Things($this->current()); }}class MyClass_Things extends RecursiveArrayIterator{ public function __construct($letter) { //do something with $letter and construct it self $array = array(); parent::__construct($array); }}$obj = new MyClass;foreach($obj as $entry){ //I expect each iteration of _Things over each iteration of _Letters //It works. Is it a bad idea?}?>