static_class

<?php 
class MyObject {
    public static $myStaticVar = 0;
    
    function myMethod() {
        self::$myStaticVar += 2;
        echo self::$myStaticVar."\n";
    }
    
}
$instanc1 = new MyObject();
$instanc1->myMethod();        //2
$instanc2 = new MyObject();
$instanc2->myMethod();        //4