<?php
// object is always passed by reference in php5
class mclass
{
 private $f;
 public function g($v)
 {
   $this->f = $v;
 }

 public function f()
 {
   echo $this->f."\n";
 }
}
$obj1 = new mclass();
$obj1->g('5');
$obj1->f();
$obj2 = $obj1;
$obj2->f();
?>

5
5