term-raw-map and local-unset-key - Need to pass <M-(left,right,up,down)> to shell

Question

As ansi-term doku tells us: any key which is not in use by emacs will be passed down to shell running inside term-mode.

As an example - I have a screen session running inside ansi-term and configured to respond to "C-o" (escape ^Oo in ~/.screenrc).

The "C-o" is not in-use by emacs, at least not in term-raw-map, so I have no trouble controlling my screen inside ansi-term.

On the other hand - <M-(arrow keys)> are in use by emacs and I want to not have those defined in term-raw-map only, otherwise I would like to keep the original mapping, even in term-line-map.

So, my thinking went - Let's undefine the offending key in term-raw-map, so that it could be passed down to whatever is running inside ansi-term.

Hence, the little piece of code, that demonstrates my conundrum.

First, I tried to define-key to nil, then tried to use a built-in local-unset-key, neither of those methods helped.

On the other hand, if I just redefine the keys to anything else, they work as expected.

My knowledge of emacs is currently insufficient to understand how to proceed to get the desired behavior.

;; For expediency I'm using only <M-left> and not all the arrow keys
;; to test - comment out one of the lines:
(defun my-local/term-hook ()
;; This does NOT work:
  (define-key term-raw-map (kbd "<M-left>") nil)
  ;; Neither does this:
  (local-unset-key (kbd "<M-left>"))

  ;; It does work flawlessly if redefined:
  (define-key term-raw-map (kbd "<M-left>") 'left-word))

(add-hook 'term-mode-hook 'my-local/term-hook)

So, to recap the question: How to change the term-raw-map in such a way, that keys already defined in other maps would be undefined in term-raw-map?

For instance, in my particular case, I'm trying to have <M-(arrow keys)> uninterpreted by emacs current active keymap and passed down to shell, as is the case with "C-o".

Answer 1

So, after reading excellent commentary for the original question, I was able to solve my problem in this way:

(defun my-term-hook ()
  (define-key term-raw-map (kbd "<M-left>")
    (lambda () (interactive) (term-send-raw-string "\e[1;3D")))
  (define-key term-raw-map (kbd "<M-right>")
    (lambda () (interactive) (term-send-raw-string "\e[1;3C")))
  (define-key term-raw-map (kbd "<M-up>")
    (lambda () (interactive) (term-send-raw-string "\e[1;3A")))
  (define-key term-raw-map (kbd "<M-down>")
    (lambda () (interactive) (term-send-raw-string "\e[1;3B")))
  )

(add-hook 'term-mode-hook 'my-term-hook)

If someone knows of a better/cleaner way, please let everyone know!