<?php
class Foo
{
    public function __clone()
    {
        $this->child = clone $this->child;
    }
}

$object = new Foo;
$object->some_value = 1;
$object->child = new stdClass;
$object->child->some_value = 1;

$deepcopy = clone $object;
$deepcopy->some_value++;
$deepcopy->child->some_value++;

echo "Object contains {$object->some_value}, child contains {$object->child->some_value}\n",
     "Clone of object contains {$deepcopy->some_value}, child contains {$deepcopy->child->some_value}\n";
?>