There is a bug with getting copy of object where 1th object has another 2th object and 2th object has another 3th object.
When i copy 2th object to any variable i must have 2th object in 1th and 2th object in variable. It must be equals but not 2 links to one object.
Look at this code and make changes as recommends in conmment.

<?
class a {
	var $i;
	function a () {
		$this->i = 1;
	}
	function set_i ($p) {
		$this->i = $p;
	}
	function get_i () {
		return $this->i;
	}
}

class b {
	function b () {
		$this->a = new a ();
	}
	function set_id ($p) {
		$this->a->set_i ($p);
	}
	
	function get () {
		return $this->a->get_i ();
	}
}

class c {
	function c () {
		$this->item = new b ();
	}
}

$cat= new c();
$z1 = $cat->item;  // Comment this line
$cat->item->set_id (12);

$z = $cat->item->a;
//$z1 = $cat->item; // Decomment this line
$cat->item->set_id (17);

echo "<br>C: i: ".$cat->item->get();
echo "<br>Z: i: ".$z->get_i ();
echo "<br>Z: i: ".$z1->get ();
if ($cat->item->get() == $z1->get ()) echo " - <font color=red>Getting BUG here. There must be '1' value!</font>";
?>