singleton

<?php

abstract class singleton {
    protected static $instance;
    final protected function __construct() {
        $this->construct();
    }

    abstract protected function construct();
        abstract protected function construct($_str);

    final public static function getInstance() {
        if (!isset(static::$instance)) {
            $className = get_called_class();
            $new_instance = new $className();
            if (!isset(static::$instance)) {
                static::$instance = $new_instance;
            }
        }
        return static::$instance;
    }

    final public function __clone() {
        trigger_error("Unable to clone singleton class __CLASS__", E_USER_ERROR);
    }

    final public function __wakeup() {
        trigger_error("Unable to unserialize singleton class __CLASS__", E_USER_ERROR);
    }
}

---------------------------- call function


<?php

require_once "util/singleton.class.php";

class users extends singleton
{
    protected static $instance;
    private $apple_id = array();

    protected function construct($_str)
    {
        //echo "users run!!!";
        $this->setUser($_str);
    }

    function getUser()
    {
        return $this->apple_id;
    }

    function setUser($_str)
    {
            //$result = mysql_query($_str);
            //$this->apple_id = mysql_fetch_assoc($result);
            echo $_str;
    }

}