class Config
{
    const host = "localhost";
    const user = "root";
    const pass = "pass";
    const name = "name";
}

final class Singleton extends Config
{
    protected static $connection;
    protected static $database = null;

    protected function Singleton () { }
    protected function __clone   () { }

    static function Prepare()
    {
        self::$connection = new mysqli
        (
            parent::host,
            parent::user,
            parent::pass,
            parent::name
        );

        if (mysqli_connect_errno())
        {
            printf
            (
                "Connection Error: %s\n ", mysqli_connect_error()
            );
        } else { echo "Databse resource found."; }
    }

    public static function Instance()
    {
        if (!isset(
            self::$database)) {
            self::$database = self::Prepare();
        }
        return self::$database;
    }
}

$instance = Singleton::Instance();