Howto override a function only locally in elisp?

[LanX]

Hi

what's the best approach to replace a function only for another
function?

My use case is to replace calls to `message' with `tooltip-show'
within some function in certain programming modes.

But I don't want to copy and change the whole function, it would be
sufficient to override locally any call to `message' with a `my-
message' function without globally messing up message.

Any idea? Perhaps with `defadvice'?

Cheers
  Rolf