singleton.php

<?php
class SingletonClass {
  private static $instance;
  private function __construct() { }
  public function __clone() {
    trigger_error('Clone is not allowed.', E_USER_ERROR);
  }
  public static function init() {
    if (!isset(self::$instance)) {
      $c = __CLASS__;
      self::$instance = new $c;
    }
    return self::$instance;
  }
  // other public, dynamic methods for singleton
}
$singleton = SingletonClass::init();