php destructor exception test

<?php
class A {
  public function __construct(){
    $this->i= new B();
  }
  public function __destruct()
  {
    $this->i->cleanup();
  }
}
class B
{
  public function __counstruct()
  {
    $this->f = 5;
  }
  public function cleanup()
  {
    if(!isset($this->used)) throw new Exception('nothing to cleanup');
  }
}
try
{
  $x = new A();
  $x->y =5;
  $x = null;
}catch(Exception $e)
{
  echo $e->getMessage(),"\n";
}