<?php
class my_class3 { 
  static $instances = 0;
  public $instance;

  public function __construct() {
    $this->instance = ++self::$instances;
  }
  public function __clone() {
    $this->instance = ++self::$instances;
  }
}
$test = new my_class3;
$test2 = clone $test;
echo $test->instance;
echo "<br />\n";
echo $test2->instance;
?>