[O] org-babel-do-load-languages

[N. Raghavendra]

I am puzzled with this definition:

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(defun org-babel-do-load-languages (sym value)
  "Load the languages defined in `org-babel-load-languages'."
  (set-default sym value)
  (dolist (pair org-babel-load-languages)
    (let ((active (cdr pair)) (lang (symbol-name (car pair))))
      (if active
          (require (intern (concat "ob-" lang)))
        (funcall 'fmakunbound
                 (intern (concat "org-babel-execute:" lang)))
        (funcall 'fmakunbound
                 (intern (concat "org-babel-expand-body:" lang)))))))
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First, the documentation string doesn't explain the significance of the
parameters SYM and VALUE.  Second, the main part of the function, that
is, the expression

(dolist (pair org-babel-load-languages) ...)

does not refer either to SYM or VALUE.  Therefore, I suggest changing
the definition along the following lines:

------------------------------------------------------------
(defun my-org-babel-do-load-languages (languages)
  "Load languages as specified by LANGUAGES.
LANGUAGES must be a list, each element of which is of the form
(LANG . ACTIVE), where LANG is the identifier of a supported
language, and ACTIVE is either t, for loading LANG, or nil, for
unloading LANG.  For a list of the supported languages and their
identifiers, see the Info node `(Org)Languages'."
  (set-default org-babel-load-languages languages)
  (dolist (pair org-babel-load-languages)
    (let ((active (cdr pair)) (lang (symbol-name (car pair))))
      (if active
          (require (intern (concat "ob-" lang)))
        (funcall 'fmakunbound
                 (intern (concat "org-babel-execute:" lang)))
        (funcall 'fmakunbound
                 (intern (concat "org-babel-expand-body:" lang)))))))
------------------------------------------------------------

I also suggest a corresponding change in Org(Languages):

------------------------------------------------------------
   By default, only ‘emacs-lisp’ is enabled for evaluation.  To enable
or disable other languages, customize the ‘org-babel-load-languages’
variable either through the Emacs customization interface, or by adding
code to the init file as shown next:

   In this example, evaluation is disabled for ‘emacs-lisp’, and enabled
for ‘R’.

     (org-babel-do-load-languages
      '((emacs-lisp . nil)
        (R . t)))
------------------------------------------------------------

Raghu.

--
N. Raghavendra <address@hidden>, http://www.retrotexts.net/
Harish-Chandra Research Institute, http://www.hri.res.in/