php設計モード-単例モード

<?php

/*

    ：           

*/

class Singleton

{

    static private $_instance = null;

    private function __construct()

    {

    

    }

    

    static public function getInstance()

    {

        if(is_null(self::$_instance))

        {

            self::$_instance = new Singleton();

        }

    }

    

    public function display()

    {

        echo "it is a singlton class function";

    }

}



//$obj = new Singleton();



//var_dump($obj);

//$obj->display();

$obj = Singleton::getInstance();



$obj1 = Singleton::getInstance();

var_dump($obj === $obj1);