Howto override a function only locally in elisp?

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

Re: Howto override a function only locally in elisp?

[Andreas Politz]

LanX <lanx.perl@googlemail.com> writes:

> 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


(require 'cl)
(flet ((message (fmt &rest args)
         (tooltip-show (apply 'format fmt args))))
  (message "Hello World"))

-ap

Re: Combining flet and defadvice

[Andreas Politz]

LanX <lanx.perl@googlemail.com> writes:

>
> Now I was trying to use this flet approach in combination with
> defadvice around, but it didn't work ...
>
> ------------------------
> (require 'pos-tip)
> (require 'cl)
>
> (add-hook 'cperl-mode-hook
> 	  (lambda ()
> 	    (cperl-toggle-autohelp)
> 	    (setq cperl-lazy-help-time 2)
>
>
> 	    (defadvice cperl-describe-perl-symbol (around cperl-describe-perl-
> symbol-tooltip)
> 	      "redirect message to tooltip"
> 	      (flet ((message (fmt &rest args)
> 	    		      (pos-tip-show (apply 'format fmt args))))
> 	    	ad-do-it))
> 	    ))
> ----------
>
> What am I missing?

You have to somehow activate the advice....

(defadvice cperl-describe-perl-symbol (around ad-name activate)
           ....)

-ap

Re: Combining flet and defadvice

[LanX]

> You have to somehow activate the advice....
>
> (defadvice cperl-describe-perl-symbol (around ad-name activate)
>            ....)
>
> -ap

ahh ...

(when testing in *scratch* the activation wasn't needed)

Great, now it works (beside some problems of pos-tip to figure out th
correct cursor position)

thanks again! :)