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 $@

I have been meaning to fix this up for a long time, but so far real work keeps getting in the way. The idea is that C-C t brings you to this week's time tracker buffer, and then you use (C-c C-x C-i/C-c C-x C-o) to start and stop timers.

The only even slightly clever is stopping the timer and saving on quitting emacs, which I borrowed from the someone on the net.

• Updated dependence on mhc removed.
• Updated 2009/01/05 Fixed week-of-year calculation

The main guts of the hack are here.

The result might look like the this (works better in emacs org-mode. C-c C-x C-d for a summary)