PHP Iterator - MySQLi

<?php

class MySQLi_Iterator implements Iterator {
    protected $classname = '\stdClass';
    protected $result = null;
    protected $current = null;
    protected $total = 0;
    protected $position = 0;
    protected $fetched = 0;

    public function __construct (MySQLi_Result $result, $classname = null) {
        $this->result = $result;
        $this->classname = $classname ?: '\stdClass';
        $this->total = $result->num_rows;
        $this->position = 0;
        $this->fetched = -1;
    }

    function rewind() {
        if($this->position > 0) {
            $this->position = 0;
            $this->fetched = -1;
            $this->result->data_seek(0);
        }
    }

    function current() {
        if($this->fetched != $this->position) {
            $this->current = $this->result->fetch_object($this->classname);
            $this->fetched = $this->position;
        }
        return $this->current;
    }

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

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

    function valid() {
        return $this->position < $this->total;
    }
}

class User {
    public $id;
    public $firstname;
    public $lastname;

    public function display () {
        return trim($this->firstname . ' ' . $this->lastname);
    }
}

$mysqli = new MySQLi('localhost', 'username', 'password', 'databasename');
$result = new MySQLi_Iterator($mysqli->query('SELECT * FROM `user`'), 'User');

foreach($result as $user) {
    echo $user->display(), PHP_EOL;
}
// Nils Corver
// Jacob Corver