From mboxrd@z Thu Jan  1 00:00:00 1970
From: Carsten Dominik <carsten.dominik@gmail.com>
Subject: Re: Not overwriting unchanged source code files when tangling
Date: Fri, 18 Nov 2011 18:02:12 +0100
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To: Holger Hoefling <hhoeflin@gmail.com>
Cc: emacs-orgmode@gnu.org


On 18.11.2011, at 14:17, Holger Hoefling wrote:

> Hi,
>=20
> I have a problem/request for org-mode and was looking for help. I am =
using org-mode to write source code files and tangle them out. I want to =
compile them using make. My problem now is that org-mode overwrites the =
old files every time I tangle them out, therefore also updating the time =
stamp - even if nothing has changed. Subsequently, when I run make, =
everything gets recompiled, not just the changed source code files as =
all time stamps have changed.
>=20
> Is there an option for org-mode to only overwrite source code files =
that get tangled out if they have truly changed?

How about changing the make file so that the dependence is on the Org =
file, not on the source file?
You could then arrange for make to call emacs in batch-mode to tangle =
the source file and then compile it?

Something along the lines of.... (untested, and probably wrong in this =
way...)

file.o: somefile.org
   emacs -batch --eval '(org-babel-tangle-file "somefile.org")'
   cc file.o ....

- Carsten=