Now:

define("E_TYPE", "Invalid type of argument");
function dbexec($connObject, $query) {
  if (is_object($connObject)) {
    if (get_class($connObject) == "dbconn") {
      if (is_string($query)) {
        return $connObject->execute($query);
      } else {
        trigger_error(E_TYPE, E_USER_ERROR);
      }
    } else {
      trigger_error(E_TYPE, E_USER_ERROR);
    }
  } else {
    trigger_error(E_TYPE, E_USER_ERROR);
  }
}

I want to be:

function dbexec((dbconn) $connObject, (string) $query) {
  return $connObject->execute($query);
}