Demo for Singleton design pattern in PHP

singletonDesignPatternDemo.php

<?php
final class ASingleTon{    
    private static $counter = 0;
    private static $instance = null;
    public static function getInstance(){
        if(!empty(ASingleTon::$instance)){
            return ASingleTon::$instance;
        }
        ASingleTon::$instance = new ASingleTon();
        return ASingleTon::$instance;
    }
    
    private function __construct(){
        ASingleTon::$counter ++;
        echo ASingleTon::$counter;
    }
    
    public function someMethod(){
        return 'here we go';
    }

}

//$obj = new ASingleTon(); // this wont work as the constructor is private

$instance = ASingleTon::getInstance();

echo $instance->someMethod();

$instance1 = ASingleTon::getInstance();

echo $instance1->someMethod();