gistfile1.php

<?php 

class Order
{
    private $orderId;
    private $state;
    private $total;
    private $creationDate;
    private $items = array();
    private $buyer;
    
    public function getOirderId()
    {
        ...
    }
    
    public function addItems($item)
    {
        ...
    }
    
    public function archive()
    {
        ...
    }
    
    public function pay()
    {
        ...
    }
    
    ...
}