Re: Multiple noweb-ref

[Ihor Radchenko <yantar92@posteo.net>]

Théo Maxime Tyburn <theo.tyburn@gmail.com> writes:

> What I would like to have, when I expand `<<bar>>` is to get all the blocks
> under A, and when I expand `<<foo>>` I get all the blocks under B. For
> now when I expand `<<foo>>` I only get the blocks under A that are not under B.
>
> Is there a way to do this with the current features of org-babel?

No, AFAIK. Not easily at least.

> Anyway I tried to hack my way trough it. It seems there are two things
> to do :
> 1) Enable noweb-ref to contain multiple references.
> 2) Accumulate references when using header-args+ or use tags to set the
> value of noweb-ref
>
> I came up with a quick patch for 1):
> modified   lisp/ob-core.el
> @@ -2910,8 +2910,11 @@ block but are passed literally to the \"example-block\"."
>  			(if (org-in-commented-heading-p)
>  			    (org-forward-heading-same-level nil t)
>  			  (let* ((info (org-babel-get-src-block-info t))
> -				 (ref (cdr (assq :noweb-ref (nth 2 info)))))
> -			    (push info (gethash ref cache))))))
> +				 (refs (cdr (assq :noweb-ref (nth 2 info)))))
> +                            (if refs
> +                                (dolist (ref (s-split "+" refs))
> +			          (push info (gethash ref cache)))
> +                              (push info (gethash refs cache)))))))

+ is a bit awkward.
Space would be more logical as separator.
Though I am wondering if people are using noweb reference names with
spaces in the wild.

> Feedback on the code is of course very welcome. Not sure if using a plus
> sign as a delimiter is clever. Also not sure if using `s-split` is a
> good idea, what would be the builtin alternative?

There is built-in `split-string'.

> For 2) I didn't check in detail how one could achieve this. I have the
> impression it would be easier to use tags. One could define a
> new variable `org-babel-set-noweb-refs-from-tags` that would be used in
> `org-babel-get-src-block-info` to generate the value of noweb-ref we
> would like to have depending on the tags of the headline of the
> block. I'll try this soonish.

I do not like the idea of using tags.

What we might do is:

1. Leave :noweb-ref's current behavior of overwriting the parent
   parameter values.
2. Add a new :noweb-ref+ parameter to accumulate multiple noweb
   reference names. The relevant function to modify is
   `org-babel-merge-params'

-- 
Ihor Radchenko // yantar92,
Org mode contributor,
Learn more about Org mode at <https://orgmode.org/>.
Support Org development at <https://liberapay.com/org-mode>,
or support my work at <https://liberapay.com/yantar92>