<?php

class DB
{
    var $connection;
    function __construct ($localhost = false, $user = false, $pass = false, $db_name = false)
    {
        if ($this->connection)
        {
            return $this->connection;
        }
        else
        {
            $this->connection = mysql_connect('localhost', 'test_user', '') && mysql_select_db ('test_db') or die ('Cannot connect to MySQL: ' . mysql_error());
            mysql_query ("SET NAMES 'utf8'");
            return $this->connection;
        }
    }
}

$a = new DB;
print_r ($a);