Re: Toggling the same key combination between two options

[Scott Frazer]

Pascal J. Bourguignon wrote:
> etay.meiri@gmail.com writes:
>
> > Hi,
> >
> > I have F8 and F9 mapped to gud-remove and gud-break (respectively) in
> > gud-mode.
> > I'd like to mimic the behaviour of Visual Studio where F9 toggles
> > between setting and removing the breakpoint. Is it possible to
> > configure emacs so that it will toggle between the two bindings every
> > time the key is pressed?
>
> (defun local-set-toggling-key (key cmd1 cmd2)
>   (interactive "KSet key locally: 
> CSet key %s locally to command: 
> CToggling key %s locally to command: ")
>   (let ((on  (gensym))
>         (off (gensym)))
>     (setf (symbol-function on)
>           `(lambda ()
>              (interactive)
>              (funcall ',cmd1)
>              (local-set-key ',key ',off))
>           (symbol-function off)
>           `(lambda ()
>              (interactive)
>              (funcall ',cmd2)
>              (local-set-key ',key ',on)))
>     (local-set-key key on)))
>
> ;; To test:
> ;; (local-set-toggling-key (kbd "<f12>")
> ;;                         (lambda () (interactive) (insert "a"))
> ;;                         (lambda () (interactive) (insert "b")))
>
>
> (local-set-toggling-key (kbd "<f9>") 'gud-break 'gud-remove)

That is pretty cool, but I don't think it's going to do what the OP
intends.  He's going to need some context to decide whether to turn
the breakpoint on or off, i.e. if there is a breakpoint on the current
line turn it off, if there isn't then turn one on.

It should be pretty easy to write, but I am not familiar with the GUD.
I assume there is some function to tell if there is a breakpoint on
the current line or not ....

Scott