Используя функцию __toString как вывести эти properties?

Как вывести названия продуктов, цены и имена владельцев через проход по итератору используя __tostring?

 <?php
  namespace lesson2;


  header('Content-Type: text/html; charset=utf-8');


  class User{
    private $name;
    private $balance;

    function __construct($name,$balance){
        $this->name = $name;
        $this->balance = $balance;
    }

    public function getName(){
        return $this->name;
    }

    public function getBalance(){
        return $this->balance;
    }

    public function __toString(){
        return "У пользователя ".$this->getName()." сейчас на счету ".$this->getBalance()."<br/>";
    }

    public function giveMoney($user, $amount){
        if($amount > $this->balance){
            return 'Недостаточно средств!'."<br/>";
        }
        else{
            $this->balance -= $amount;
            $user->balance += $amount;
            return "Пользователь ".$this->name." перечислил ".$amount." пользователю ".$user->name."<br/>";
        }

    }

  }

  abstract class Product
  {
    private $name;
    private $price;
    private $owner;
    static private $products = array();

    function __construct($name, $price, $owner)
    {
        $this->name = $name;
        $this->price = $price;
        $this->owner = $owner;
    }

    public function setOwner(User $user)
    {
        $this->owner = $user;
    }

    public static function getProductIterator()
    {
        return new class (self::$products) implements \Iterator {
            private  $position = 0;
            private  $array;

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

            public function rewind()
            {
                $this->position = 0;
            }

            public function current()
            {
                return $this->array[$this->position];
            }

            public function key()
            {
                return $this->position;
            }

            public function next()
            {
                ++$this->position;
            }

            public function valid()
            {
                return isset($this->array[$this->position]);
            }
        };

    }

    public static function registerProduct($product)
    {
        if (in_array($product, self::$products, true)) {
            echo 'Введены одинаковые продукты ' . '</br>';
        } else {
            array_push(self::$products, $product);
        }
    }
  }

  class Processor extends Product{
    private $frequency;
    public function __construct($name, $price, $owner,$frequency)
    {
        parent::__construct($name, $price, $owner);
        $this->frequency=$frequency;
    }

  }

  class Ram extends Product{
    private $type;
    private $memory;
    public function __construct($name, $price, $owner, $type, $memory)
    {
        parent::__construct($name, $price, $owner);
        $this -> type = $type;
        $this -> memory = $memory;
    }
  }


    ///////////////////////////////////////////

    $a = new Processor("Intel",4500,"Kirill",3.9);
    Product::registerProduct($a);
    Product::getProductIterator();