Re: [ANN] lisp/ob-tangle-sync.el

[Mehmet Tekman <mtekman89@gmail.com>]

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Ihor Radchenko <yantar92@posteo.net> writes:

> Do I understand correctly that your package is adding the following new
> features:
>
> 1. Automatically manages balanced
>    `org-babel-tangle'/`org-babel-detangle' in Org sources and target
>    buffers.
> 2. Attempts to make more fine-grained tangling/detanging functionality
>    by controlling tangling behaviour on per-src-block basis (via
>    :tangle-sync skip/pull/export/both)
>

That is correct

> If so, I think that (2) probably belongs to the main babel code
> (`org-babel-tangle' and `org-babel-detangle'). Since you are
> contributing to Org directly, you are free to modify these functions as
> you need.
>
> Note that your current approach with `org-babel-tangle-sync-synchronize'
> will give unexpected results when one edits multiple src blocks or the
> corresponding tangled source in multiple places - the :tangle-sync value
> is only checked at point and `org-babel-tangle'/`org-babel-detange' is
> then called for the whole buffer, not just for the current code block.

That's... a really good point. I didn't consider that I'm calling a
tangle or detangle function on an entire file based on the
=:tangle-sync action= of a single block... which might have different
actions in another block for the same file!

I've attached a toy.org file which should explain what the desired
action would be in such a situation, and I fully agree that I will
likely need to modify the current tangle and detangle code so that the
sync direction is on a per-block basis, and not per-file.

I will work on this a bit more and submit a full patch with this in
mind.

Best,
Mehmet

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#+TITLE: Sync Many Blocks
#+PROPERTY: header-args  :tangle /tmp/default_tangle.txt :comments yes

* Default Tangle

 The =:tangle= target here is given by the ~PROPERTY~ header.  It is
 made up of three parts which synchronize with the tangled destination
 file in 3 different ways as given below: 

** File Contents
 
*** Free Head

#+begin_src conf
  This is some text that can be synced both ways
#+end_src

*** Pull Middle

#+begin_src conf  :tangle-sync import
  The middle text only retrieves from the default tangle file
#+end_src

*** Push tail

#+begin_src conf  :tangle-sync export
  This last piece of text only exports from the source org mode file.
#+end_src

* Desired Function

When =org-babel-tangle= is called, only the [[Free Head]] and [[Push tail]]
sections are tangled. The middle section in the tangled file is
_skipped_.

When =org-babel-detangle= is called, only the [[Pull Middle]] section is
updated here. The other two sections are _skipped_.

* Why skipped?

The functions suffixes explicitly state a direction (=tangle= /
=detangle=), and it's probably important that we retain this
directionality.

If we want to synchronize all blocks (i.e. import the middle section
from the tangled file during =org-babel-tangle=, and export the head
and tail sections during =org-babel-detangle=), then perhaps we set a
specific custom variable =(setq org-babel-tangle-alwayssync t)=?

Or, we create a specific function =org-babel-sync= (for lack of better
name) which tangles/detangles in whatever desired direction the source
block specifies.