Re: Optional arg via lambda

[Thorsten Jolitz <tjolitz@gmail.com>]

"Sebastien Vauban" <sva-news@mygooglest.com>
writes:

> Hello,
>
> In my config, I have written this to check whether Org 8 is installed
> when trying to call the "export dispatcher" (bound, here, to `C-x
> C-e').
>
>     (define-key org-mode-map
>       (kbd "C-c C-e")
>       (lambda ()
>         (interactive)
>         (if (fboundp 'org-export-dispatch)
>             (org-export-dispatch)
>           (message "Upgrade to Org 8!"))))
>
> However, the above code drops the optional `C-u' which we can use when
> calling `org-export-dispatch'. IOW, `C-u C-x C-e' does the same as
> `C-x C-e'.
>
> I've tried adding an optional arg to the `lambda' and to pass it to
> the funcall of `org-export-dispatch', as shown here:
>
>     (define-key org-mode-map
>       (kbd "C-c C-e")
>       (lambda (&optional arg)
>         (interactive)
>         (if (fboundp 'org-export-dispatch)
>             (progn
>               (message "arg: %s" arg)
>               (funcall 'org-export-dispatch arg))
>           (message "Upgrade to Org 8!"))))
>
> But this does not work: `org-export-dispatch' is well called when
> pressing both `C-x C-e' and `C-u C-x C-e', but the `C-u' is never
> passed along to the original `org-export-dispatch' function.
>
> What am I missing?

does
      ,------------------------
      | (lambda (&optional arg)
      |   (interactive "P") ...
      `------------------------

make a difference?

-- 
cheers,
Thorsten