php でシングルトン

<?php

class Foo {
  private function __construct() {
    $this->t = 'initialized Foo';
  }

  public $t;

  public static function &getFooInstance() {
    static $foo_instance;
    if( !isset( $foo_instance ) ) {
      $foo_instance = &new Foo;
    }
    return $foo_instance;
  }

}

$f = Foo::getFooInstance();

echo $f->t . "\n";

/*
$g = new Foo;

echo $g->t . "\n";
*/

?>