Re: layout org-babel menu WAS: About org-babel menu

[Eric Schulte <eric.schulte@gmx.com>]

Torsten Wagner <torsten.wagner@gmail.com> writes:

> Hi,
>
> for me the biggest "trouble" with babel is to remember the possible
> keywords in the header for different languages.
> There were a lot of ongoing syntax change which did not make it easier
> for me to remember all this.
> Thus a menu which is organised by languages offering all possible
> settings for each language would be very helpful.
> |
> Python
> |    |
> |  export - code - result - both - none
> |    |
> |  tangle - no - yes- filename
> |   |
> |  result - value - output
> |  |
> | ...
> |
> ...
>
> Not sure how effectual this would be in a main menu. It would be
> definitely awesome in a context menu
>
> That would be (copied from worg) [*] indicates cursor position
>
> #+NAME: factorial
> #+BEGIN_SRC haskell [*] :results silent :exports code :var n=0
>
> a context menu would appear presenting all possible header arguments for haskell
>
> #+NAME: factorial
> #+BEGIN_SRC haskell :results [*] :exports code :var n=0
>
> a context menu presenting all possible values for the header argument
> :results in haskell
> I guess that together with the possibility to call this menu by
> keyboard strokes or alternatively show the same infos in the
> minibuffer would be a great win for babel and it would make many
> questions here on the list unnecessary.
> Furthermore, any change or extension in the syntax for a certain
> language would be directly reflected to the end-user. E.g., If I
> suddenly see the menu entry :exports 3dprint, I would be curious and
> check it out on worg and the manual ;)
>
> Totti
>

Hi,

I've put together a first pass at such support for interactive header
argument look up.  Please evaluate this elisp code [1] in your *scratch*
buffer, then in an Org-mode buffer insert a code block like the
following with the point at [*], and press tab.

#+begin_src R :[*]
  :foo
#+end_src

You should see an auto-completion list showing which header arguments
are available and (for those with known arguments) which arguments may
be specified.  This includes language specific header arguments, i.e.,
the R code block above suggests about twice as many possible header
arguments as an elisp block.  Note this "expand on tab after :" behavior
is active on "#+headers:" lines as well.

This makes use of the `org-babel-common-header-args-w-values' variable
which holds header argument names and completions, as well as the
org-babel-header-arg-names:lang variables.

Does this seem like a good interface?

Is it missing any important functionality?

Best,

Footnotes: 
[1]  
;; Add support for completing-read insertion of header arguments after ":"
(defun org-babel-header-arg-expand ()
  "Call `org-babel-enter-header-arg-w-completion' in appropriate contexts."
  (when (and (= (char-before) ?\:) (org-babel-where-is-src-block-head))
    (org-babel-enter-header-arg-w-completion (match-string 2))))

(defun org-babel-enter-header-arg-w-completion (&optional lang)
  "Insert header argument appropriate for LANG with completion."
  (let* ((lang-headers-var (intern (concat "org-babel-header-arg-names:" lang)))
         (lang-headers (when (boundp lang-headers-var)
                         (mapcar #'symbol-name (eval lang-headers-var))))
         (headers (append (mapcar #'symbol-name org-babel-header-arg-names)
                          lang-headers))
         (header (org-completing-read "Header Arg: " headers))
         (args (cdr (assoc (intern header)
                           org-babel-common-header-args-w-values)))
         (arg (when (and args (listp args))
                (org-completing-read
                 (format "%s: " header)
                 (mapcar #'symbol-name (car args))))))
    (insert (concat header " " (or arg "")))
    (cons header arg)))

(add-hook 'org-tab-first-hook 'org-babel-header-arg-expand)

-- 
Eric Schulte
http://cs.unm.edu/~eschulte/