Hello everyone,

I'm not going to talk about literate programming, because there are already great articles about it, like this one: Introduction to Literate Programming by Howard the Geek.

Instead, I want to talk about my memory problem. Many times— and when I say many, I mean many —when I need to modify a script or a program, I just go to the code and make the change. As you’d expect. But sometimes I review the configuration in the org document where the script is located, and then I run C-c C-v C-t to generate the code, and it overwrites the changes I made directly in the file: F**k!

So I decided to add this little snippet of code to a section in all my org files that contain any script, so that it automatically inserts a header with information about where it came from.

* Export Data
#+NAME: export-data
#+BEGIN_SRC elisp :var comment=";;" :results value :tangle no
  (format "%s Org-babel generated.\n%s Export date: %s\n%s File: %s"
          comment
          comment
          (format-time-string "%Y-%m-%d %H:%M:%S")
          comment
          (buffer-file-name))
#+END_SRC

This way, I can use it in any file like this:

* File =early-init.el=
#+begin_src emacs-lisp :tangle ~/.config/emacs/early-init.el :noweb yes
  ;; -*- lexical-binding: t; -*-

  <<export-data()>>

  ;; Match theme color early on (smoother transition).
  ;; Theme loaded in features/ui.el.

  ...
  #+end_src

The function has a parameter comment which defaults to ;;, but we can use it to change the comment prefix by passing another one:

<<export-data(comment="#")>>

The result it's something like that:

;; -*- lexical-binding: t; -*-

;; Org-babel generated.
;; Export date: 2025-04-11 10:12:47
;; File: /home/cnoceda/Qsync/config/emacs/config_files/emacs.org

;; Match theme color early on (smoother transition).
;; Theme loaded in features/ui.el.

...

Now, when I open the file, I see that comment and I use find-file-at-point or embark to open the org file.

As I write these lines, I realize that maybe this can already be done natively with org-babel, but I don’t know how. In any case, here’s a trick we can always adapt to suit our needs.

Regards!