Récupération des variables

 $link = mysql_connect ($this->host, $this->user, $this->pass);

<?php
class config {
private $host='localhost'// db host
        ,$user='root' // db username
        ,$pass='' // db password
        ,$db='db' ; // db name
public $link;

 function __construct(){
   $this->connect();
}

  private function connect()   {
   $this->link = mysql_connect ($this->host, $this->user, $this->pass);
   mysql_select_db ($db,$link);
   }

}
?>

 require_once "config.php";
 $cfg= new config();
 $link = $cfg->link;