Re: Elisp newbie trying a derived mode (clarifying intent)

[Kevin Rodgers]

Mathias Dahl wrote:
> "davex" <dmagill@attglobal.net> writes:
>
> > let me clarify the above--I'd like to make this simple to use
> > regularly, hence have a single keystroke call
> > dired-do-shell-command, with the correct shell command (to write out
> > the filename) hard-coded-- i suppose i could do this as a keyboard
> > macro, but if I can do a derived mode in a clean concise way, I
> > could apply this skill elsewhere.  Am I on the right track? Is a
> > derived mode a common useful solution?
>
> To me it seems overkill to create a new mode for this. Just create
> your new defuns and bind a free key to one of them. You can add a hook
> to dired mode that binds this key each time dired starts.

Definitely.

> I have this in my .emacs:
>
> ;; if dired's already loaded, then the keymap will be bound
> (if (boundp 'dired-mode-map)
>     ;; we're good to go; just add our bindings
>     (my-dired-init)
>   ;; it's not loaded yet, so add our bindings to the load-hook
>   (add-hook 'dired-load-hook 'my-dired-init))

Why not just unconditionally (add-hook 'dired-mode-hook 'my-dired-init)?

> `my-dired-init' does a lot of extra stuff I want in dired, like these
> bindings, for example:
>
>   ...
>   (define-key mode-specific-map "xp" 'dired-w32-open-files)
>   (define-key dired-mode-map [return] 'joc-dired-single-buffer)
>   ...

I generally prefer (local-set-key KEY COMMAND) to
(define-key 'some-mode-map KEY COMMAND)

For davex's situation, I think the command he wants would be
something like:

(defun davex-dired-do-shell-command (&optional next-files)
  "Run the \"davex.exe\" command on the marked files.
If no files are marked or a specific numeric prefix arg is given,
the next ARG files are used.  Just \\[universal-argument] means \
the current file."
  (interactive "P")
  (dired-do-shell-command "davex.exe" ; or "davex.exe *"
                          next-files    ; prefix arg
                          (dired-get-marked-files t next-files)))

--
Kevin