title: static instance in PHP
body: <p>Why does the following code print "1,1,1," instead of "4,5,6,"?  </p>
  
  <pre><code>
  class MyClass {
    // singleton instance
    private static $instance = 3;
  
    function __construct() {
   $instance++;
   echo $instance . ",";
    }
  }
  
  for($i = 0; $i &lt; 3; $i++) {
   $obj = new MyClass();
  }
  </code></pre>