erro in db class

what /where is error ?

include("config.php");
class database
{
    global static     $host    = $c['server']['name'] ;
    global static     $user    = $c['server']['user'];
    global static     $pass    = $c['server']['password'];
    global static     $port    = $c['server']['port'];

     public static function connection()
        {
            self::$host    ;
            self::$user    ;
            self::$port    ;
            self::$pass    ;
            
            do
                {
                    $link    = mysql_pconnect(self::$host.":".self::$port, self::$user, self::$pass) or die (mysql_errno()." : ". mysql_error()); ;
                }
            while ($link == false);      
        }
}    
$db= new database;
$db->connection();