Re: Seeking Advice about refactoring and advice snippet

[Filipe Silva <filipe.silva@gmail.com>]

Well, someone at emacs.stackexchange pointed out the the &rest keyword used
in my ninrod--protection function was to blame. That fixed the problem.

thanks!

On Fri, Feb 10, 2017 at 9:43 AM, Filipe Silva <filipe.silva@gmail.com>
wrote:

> Dear good people of the emacs help list,
>
> I have a working snippet that advices both kill-buffer and
> kill-this-buffer to not kill the *scratch* buffer:
>
>       (defun ninrod/scratch-bodyguard (buffer-assassin &rest arguments)
>         (let ((buffer-to-kill (buffer-name (current-buffer))))
>           (if (equal buffer-to-kill "*scratch*")
>               (message "DENIED! don't kill my precious *scratch*!!")
>             (apply buffer-assassin arguments))))
>       (defun ninrod/scratch-protection (buffer-assassin &rest arguments)
>         (let ((buffer-to-kill (car arguments)))
>           (if (equal buffer-to-kill "*scratch*")
>               (message "DENIED! don't kill my precious *scratch*!!")
>             (apply buffer-assassin arguments))))
>       (advice-add #'kill-this-buffer :around #'ninrod/scratch-bodyguard)
>       (advice-add #'kill-buffer :around #'ninrod/scratch-protection)
>
> The problem is that these lines:
>
>       (message "DENIED! don't kill my precious *scratch*!!")
>      (apply buffer-assassin arguments))))
>
> Are repeated in both functions, so I thought that I could apply the DRY
> principle and refactor the snippet to this:
>
>     (defun ninrod--protection (buffer-assassin buffer-to-kill &rest
> arguments)
>       (if (equal buffer-to-kill "*scratch*")
>           (message "DENIED! don't kill my precious *scratch*!!")
>         (apply buffer-assassin arguments)))
>     (defun ninrod/scratch-bodyguard (buffer-assassin &rest arguments)
>       (let ((buffer-to-kill (buffer-name (current-buffer))))
>         (ninrod--protection 'buffer-assassin buffer-to-kill arguments)))
>     (defun ninrod/scratch-protection (buffer-assassin &rest arguments)
>       (let ((buffer-to-kill (car arguments)))
>         (ninrod--protection 'buffer-assassin buffer-to-kill arguments)))
>     (advice-add #'kill-this-buffer :around #'ninrod/scratch-bodyguard)
>     (advice-add #'kill-buffer :around #'ninrod/scratch-protection)
>
> This causes all hell to break loose. Now I can't even close emacs, because
> apparently emacs tries to kill all buffers
> and as I've just tampered with the kill buffer functions, well, it's bad.
> Very bad.
>
> I know I mean well, but I'm must be doing something very stupid. For
> starters, I don't know if I can really pass around
> functions as parameters? So it could be that?
>
> How would you refactor that snippet to apply the dry principle?
>
> thanks in advance,
>
> Filipe.
>
>