<pre>
 
<?php
$assigned   =  $instance;
$reference  =& $instance;
 
$instance->var = '$assigned will have this value';
 
$instance = null; // $instance and $reference become null
 
var_dump($instance);
var_dump($reference);
var_dump($assigned);
?>
 
 
<hr>
 
The above example will output:
 
NULL
NULL
object(SimpleClass)#1 (1) {
   ["var"]=>
     string(30) "$assigned will have this value"
}
</pre>