OOP: Návrh, použití - je to správné?

<?php
class Login{
  protected $ip,
            $alvl,
            $mail,
            $nick,
            $accID,
            $chat_time;

  public function __construct(){
    throw new exception("Pristup k tride ".get_class($this)." byl odmitnut.");
  }

  protected function login($userData){
    $this->ip         = $_SERVER['REMOTE_ADDR'];
    $this->alvl       = $userData[4];
    $this->mail       = $userData[3];
    $this->nick       = $userData[0];
    $this->accID      = $userData[2];
    $this->chat_time  = time();
  }
}

class Chat extends Login{
  public function __construct($userData){
    if(!is_array($userData)) throw new exception("Data nejsou typu Pole!");
    if(count($userData)!=5 || in_array("",$userData)) throw new exception("Nektera data nebyla vyplnena.");
    $this->login($userData);
  }
  public function GetData(){
    echo "Nick: {$this->nick}| AccountID: {$this->accID}| E-mail: {$this->mail}| Admin level: {$this->alvl}| IP: {$this->ip}| Loaded: {$this->chat_time}";
  }
}

try{
  $chat = new Chat(Array("nick","password","accountID","email","0"));
  $chat->GetData();
}
catch(exception $err){
  echo "Chyba: ".$err->getMessage();
}
?>