Re: [O] Exporting noweb-ref's without disabling org-babel processing

[Diego Zamboni]

Hi Chuck,

Thanks for your answer - I didn't know about that behavior of  #+CALL, and I'm sure it will be useful sometime.

However, this is not exactly what I was getting at. Here's what I want:

1. First of all, my code needs to tangle correctly - for this I use :noweb and :noweb-ref in some of the chunks, to structure things better. org-babel-tangle produces a working source file.

2. Upon export, most source blocks should export as-they-are. However, when I use :noweb or :noweb-ref, I want two things:

   a) Noweb chunk names should not be expanded upon export - e.g. <<super-duper-code>> should be exported like that

   b) Chunks with :noweb-ref should be identified by their chunk name in the exported code, e.g. prepended by "<<super-duper-code>>=" in the line before the chunk name.

3. As part of the explanation in my org file, I have some other source blocks (e.g. Ditaa) which are not part of  the tangle output, but rather I use  to produce diagrams or other stuff. For these, I need ":exports results" behavior.

And here's my current status:

1. Works, basic org-babel functionality, no issues :)

2.a. Works by setting ":noweb no-export", no problems.

2.b. Works by modifying my exporter to include the necessary text in the exported output. *However*, the exporter can only access the :noweb-ref header argument  if the =org-export-use-babel= variable is set to =nil=. Otherwise, it seems that all org-babel related headers (including :noweb, :noweb-ref and :exports) are removed from the block before it gets passed to the exporter functions.

3. Only works if =org-export-use-babel= is set to =t=, since otherwise org-babel (who  does the selection of what gets exported based on  :exports) never gets called.

Basically, my problem is the contradiction between (2.b) and (3) above, with respect to the org-export-use-babel variable. What I would like to know is if there is a way to keep the :noweb and :noweb-ref  header arguments in the block, even after org-babel processes them.

For (2.b), I  also experimented with setting =org-babel-exp-code-template=, unfortunately I encountered two problems:

1. =org-fill-template= sorts keys  by length, which meant that when "%noweb-ref" appears in the template, it always gets interpreted as "%noweb" followed by the string "-ref".

2. I only want the value of :noweb-ref to be output when the parameter is specified, but =org-fill-template= doesn't handle that sort of logic - the header argument is always expanded in the template, even when its value might be missing or "no".

So, I'm still looking for a good solution to my problem. In the meantime, I can generate my Ditaa diagrams separately and just include  the output in my org file, which is not tragic but not the most elegant :)

Hope this further clarifies things!

Best,

--Diego

On Wed, Oct 23, 2019 at 6:51 PM Berry, Charles <address@hidden> wrote:

Diego,

I am not sure I understand. Here is my interpretation:

You wish to have `:exports both' behavior in your org export.

You want noweb references in the exported code to render as angle-bracketed chunk names, such as <<my-code>> rather than being expanded in place.

If that is what you want, you can use the feature of CALL keywords that resets the header arguments for the src block it calls to obtain different behavior with the same code. For example:

#+begin_src org
  ,#+name: template-chunk
  ,#+begin_src emacs-lisp :noweb no
  (concat c b a
  <<super-duper-code>>
  )
  ,#+end_src

  ,#+CALL: template-chunk() :noweb yes :var a="A" b="B" c="C"

  ,#+begin_src emacs_lisp :noweb-ref super-duper-code
  (concat a b c)
  ,#+end_src
#+end_src

exports as

--8<---------------cut here---------------start------------->8---
,----
| (concat c b a
| <<super-duper-code>>
| )
`----

,----
| CBAABC
`----


,----
| (concat a b c)
`----
--8<---------------cut here---------------end--------------->8---

HTH,

Chuck

> On Oct 22, 2019, at 1:29 PM, Diego Zamboni <address@hidden> wrote:
>
> Hi,
>
> I'm working on a Leanpub Markua exporter (not quite complete yet but already usable, if you are interested: https://github.com/zzamboni/ox-leanpub/tree/book-and-markua)
>
> I would like to include the value of :noweb-ref for code blocks in exported output, like noweb originally did, e.g. something like this:
>
> #begin_src emacs_lisp :noweb-ref super-duper-code
> ...
> #end_src
>
> to produce something like this in the export:
>
> <<super-duper-code>>=
>  ...
>
> After much poking around, I figured that the :noweb and :noweb-ref header args are removed by org-babel *before* the src block makes it to the exporter. I also discovered that by setting org-export-use-babel to nil I could disable this behavior, which means that my exporter can access the :noweb-ref argument by parsing the :parameters property (see https://github.com/zzamboni/ox-leanpub/blob/book-and-markua/ox-leanpub-markua.el#L388).
>
> This was good for my original purpose, but I just realized that this also disables other useful org-babel features on export, such as the processing of the :exports header argument, which means that both code and results are always included in the export regardless of what :exports says :)
>
> I have tried using org-babel-exp-code-template, but unfortunately if I try to use "%noweb-ref" as a key in its value, it gets replaced by the value of :noweb followed by "-ref" in every case.
>
> Is there some other way of accessing org-babel header arguments like :noweb-ref from the exporter, but without having to disable org-babel processing completely? Any other ideas for achieving what I want?
>
> Thanks for any ideas,
> --Diego
>