php单例模式实现方法分析

<?php
/**
 * @copyright 2013 maguowei.com
 * @author ma guowei <imaguowei@gmail.com>
 */
/**
 * 单例模式
 * class single
 */
class single
{
  private $name;
  private static $single;
  private function __construct()
  {
  }
  public static function init()
  {
    if(empty(self::$single))
    {
      self::$single = new single();
    }
    return self::$single;
  }
  public function getname()
  {
    return $this->name;
  }
  public function setname($name)
  {
    $this->name = $name;
  }
}
$s = single::init();
$s->setname('hhhh');
echo '$s:'.$s->getname();
unset($s);
$m = single::init();
echo '$m:'.$m->getname();