Static properties in classes

<?php

class Anything
{
    public static $current = 'initial value';
    
    protected $value;
    
    /**
     * Anything constructor.
     *
     * @param $value
     */
    public function __construct($value)
    {
        $this->value = $value;
    }
    
    public function select()
    {
        self::$current = $this->value;
    }
}

var_dump(Anything::$current);

$o1 = new Anything('object 1');
$o2 = new Anything('object 2');

$o1->select();
var_dump($o1::$current);

$o2->select();
var_dump($o1::$current);