bingung ma OOP gan..

validasi.php
<?php
    include ('user.php');

    class validasi extends user{//extend untuk menurunkan sifat yang ada pada class user pada kelas baru
        //juga untuk mendapatkan hasil inisialisasi dari kelas user tersebut
        public function login($email, $pass){//fungsi
        /*$vEmail = mysql_query("select email from user");
        $vPass = mysql_query("select password from user");*/
        $qry = mysql_query("select * from user where email = '$email' and pass = '$pass'");
        $xec = mysql_fetch_array($qry);
        if($xec!=null){
            echo '<h1><blink>berhasil login !';
            }
            else echo '<strong><h1><blink>password dan email anda salah';
        }
    }

    $log = new validasi('');
    echo $log->login($this->email, $this->pass);
?>

user.php
<?php

    include ('db.php');
    class user{
        public $email;
        public $pass;

        public function __construct($pass){//construct
            $this->email = $_POST['email'];
            $this->pass = $_POST['pass'];

            /*$vEmail = mysql_query("select email from user");
            $vPass = mysql_query("select password from user");*/
        }
    }
?>