Remapping Emacs Commands

Question

I want to remap forward-sexp to matlab-forward-sexp in matlab-mode.

Currently I do this:

(define-key matlab-mode-map [remap forward-sexp] 'matlab-forward-sexp-safe)

but when I type M-x forward-sexp in matlab-mode I still get the old behaviour. Why? Does it only work when I call forward-sexp through a keyboard shortcut?

when I type C-h f forward-sexp everything seems ok:

forward-sexp is an interactive compiled Lisp function in `lisp.el'.

It is remapped to `matlab-forward-sexp-safe', which is bound to C-M-f,
<C-M-right>, ESC <C-right>.

(forward-sexp &optional ARG)



For more information check the manuals.

Move forward across one balanced expression (sexp).
With ARG, do it that many times.  Negative arg -N means
move backward across N balanced expressions.
This command assumes point is not in a string or comment.

This function is advised.

After-advice `ctx-flash'.

[back]

Answer 1

If you really want to change the behavior of the function, you can use forward-sexp-function.

Also you may like to check out Emacs-24's octave-mode, which uses SMIE for parsing, making forward-sexp automatically jump over actual Octave syntactic elements rather than only parens/brackets/braces.

Answer 2

Yes, the [remap] syntax is explicitly for key bindings. When a binding would have invoked the old function, the remapping causes it to invoke the new one instead. That does not alter the definitions of either function, however -- they can still be called directly.

For details, see M-: (info "(elisp) Remapping Commands") RET

A recent change in Emacs 24 has clarified this help text, so it would now read as follows:

forward-sexp is an interactive compiled Lisp function in `lisp.el'.

Its keys are remapped to `matlab-forward-sexp-safe'. Without this remapping, it would be bound to C-M-f, <C-M-right>, ESC <C-right>. .