gistfile1.php

<?php

class A {
    
    private $b;

    public function __construct($b) {
        $this->b = $b;
    }

    public function getB($from) {
        return $from->b;
    }
}

$foo = new A(23);
$bar = new A(42);
var_dump($bar->getB($foo));


int(23)