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emacsinitializationelispkey-bindings

bind key to negative-argument + command in emacs

I am trying to bind to M-b a command preceded by a negative argument. I post my code.

working

(global-unset-key (kbd "M-f"))                                                         
(global-set-key (kbd "M-f") 'forward-whitespace)

not working 

(global-unset-key (kbd "M-b"))                                                         
(global-set-key (kbd "M-b") (lambda () (interactive) (negative-argument(forward-whitespace))))

How can I make it working?

Solution

  • The specific issue you have is solved easily:

    (global-set-key (kbd "M-b") (lambda () (interactive) (forward-whitespace -1)))

    You might wonder if you can write a macro that would call an arbitrary command interactively with negative argument.

    It is not really hard:

    (defmacro call-with-negative-argument (command)
  `(lambda ()
     (interactive)
     (prefix-command-preserve-state)
     (setq prefix-arg '-)
     (universal-argument--mode)
     (call-interactively ,command)))
(global-set-key (kbd "...") (call-with-negative-argument forward-whitespace))

    but, really, any compliant function would also work fine like this:

    (defmacro call-with-negative-argument (command)
  `(lambda ()
     (interactive)
     (,command -1)))