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I'm experimenting with Uncle Dave's config which is using a minimum init.el to launch config.org, which is full of elisp babel source blocks. Here's his relevant launching code:

(when (file-readable-p "~/.emacs.d/config.org")
  (org-babel-load-file (expand-file-name "~/.emacs.d/config.org")))

However, I've seen this:

(require 'org)
(require 'ob-tangle)
(org-babel-load-file (expand-file-name "~/.emacs.d/myemacs.org"))

which seems to want (require 'ob-tangle) (See here). The Uncle Dave setup is working fine. I guess I don't know how it's tangling (which means running all the code blocks in the org file, right?) without somehow being told to. But then what is org-babel-tangle-file doing other than running all the code blocks in a file? And then there's the :tangle yes parameter on an individual code block. I'm missing something here.

147pm
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2 Answers2

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Here's what Nick Dokos (who has helped me often) over at the org-mode mail list says:

...tangling does not run code blocks: it just writes them out to (one or many) different file(s). org-babel-load-file calls org-babel-tangle which is an autoloaded function, so when it is called, emacs arranges to load the file that defines it (i.e. ob-tange.el[c]). So you don't need to to (require 'ob-tangle) separately.

However, I don't know all the ins and outs of tangling in org-mode yet. But I would guess attaching :tangle no to a block would keep it out of the tangle file.

This is what I had been doing -- at least for small bunches of code:

#+name: setup
#+BEGIN_SRC scheme :session ch1
(require math)
#+END_SRC

#+RESULTS: setup

# Local Variables:
# eval: (progn (org-babel-goto-named-src-block "setup") (org-babel-execute-src-block))
# End:

i.e., I'm using Emacs' local file variable capability to have a Racket module loaded, and, as a bonus, start up a REPL session.

Another angle is to use org-mode's Library of Babel capability.

147pm
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  • Cool trick =) Would you mind expanding on why you have your setup this particular way? I feel I'm missing something that could be useful here. – Daniel Apr 03 '18 at 22:17
  • The particular file this `#+name: setup` and the local file variable is in requires Racket's math module. It wouldn't make any sense to have it start as part of Emacs' general initialization. – 147pm Apr 04 '18 at 02:43
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The way I configured my init.el as a init.org is similar to the one you are quoting from Uncle Dave. I am not using ob-tangle for parsing all the src blocks to another file using :tangle as a argument. I just bind org-babel-load-file to a key so as to reload it whenI make changes. 

(global-set-key (kbd "C-c i")
(lambda() (interactive)(org-babel-load-file "~/.emacs.d/init.org")))
manandearth
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  • Thanks for the tip. Will implement. But what is the difference between `org-babel-load-file` and tangle stuff? – 147pm Apr 02 '18 at 22:35
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    I tried to call from the init.org file but it end up with a recursive call. I am therefore not sure how the tangle method works, since in the example that I find online there is no `:tangle` in the src header. normaly tangling will mean creating the one .el file from all the src blocks in te org file, which is what happens anyway when you call `org-babel-load-file` – manandearth Apr 03 '18 at 08:56
  • I think I'll ask over at the org-mode mailing list. – 147pm Apr 03 '18 at 12:07
  • please post your findings here @147pm, The documentation is very minimal.. – manandearth Apr 03 '18 at 13:03
  • Yeah, this whole "minimal" org-mode docs then people asking tons of questions that don't really get categorized or summarized into an O'Reilly-style book is a real treadmill. But then Emacs is vast. Alas. – 147pm Apr 03 '18 at 13:11