I have lately been using org-mode literate programming to generate
example code and beamer slides from the same source. I hit a wall
trying to re-use functions in multiple files, so I came up with the
following hack. Thanks 'ngz' on #emacs and Charles Berry on the
org-mode list for suggestions and discussion.
(defun db-extract-tangle-includes ()
(goto-char (point-min))
(let ((case-fold-search t)
(retval nil))
(while (re-search-forward "^#[+]TANGLE_INCLUDE:" nil t)
(let ((element (org-element-at-point)))
(when (eq (org-element-type element) 'keyword)
(push (org-element-property :value element) retval))))
retval))
(defun db-ob-tangle-hook ()
(let ((includes (db-extract-tangle-includes)))
(mapc #'org-babel-lob-ingest includes)))
(add-hook 'org-babel-pre-tangle-hook #'db-ob-tangle-hook t)
Use involves something like the following in your org-file.
#+SETUPFILE: presentation-settings.org
#+SETUPFILE: tangle-settings.org
#+TANGLE_INCLUDE: lecture21.org
#+TITLE: GC V: Mark & Sweep with free list
For batch export with make, I do something like
%.tangle-stamp: %.org
emacs --batch --quick -l org -l ${HOME}/.emacs.d/org-settings.el --eval "(org-babel-tangle-file \"$<\")"
touch $@