bug#13305: 24.2; describe-function gives incorrect function location information (for functions changed in a hook?)

[Mark Lillibridge <mdl@alum.mit.edu>]

Stefan Monnier <monnier@iro.umontreal.ca> writes:

>  >     Basically, this replaces the built-in version of
>  > rmail-summary-output with a patched version; the patching is done only
>  
>  Don't do that.  Use defadvice or advice-add instead.

    For some reason I was thinking that changes to interactive didn't
work properly with advice.  Just using defun can be more convenient than
advice, however, when you are in a hurry for a temporary patch.

    It's too bad there isn't a macro for replace-defun that acts
syntactically identical to defun except that it uses advice to patch
lazily the built-in (e.g., part of Emacs distribution) function.  This
would be a lot easier for users to understand and use.  For that matter,
what would be really useful is a small (10-20 page?) guide to patching
Emacs with this sort of useful information.  Yes, I know there is a 800+
page elisp manual that contains a lot of this information somewhere
(maybe?)  But the reality is that the average person trying to patch
Emacs doesn't have time to read the manual and limits themselves to
Google searches.  You don't discover advice that way.

- Mark