Multiple noweb-ref

Multiple noweb-ref

[Théo Maxime Tyburn]

Hi,

I have several code blocks that I label using `:noweb-ref label`. I set
them for all blocks under a subtree by setting the org property
`header-args+` of the root of the subtree to `:noweb-ref label`.

Now with this approach, I can't accumulate `noweb-ref` like I could do for
tags. I would like all blocks under a subtree A to have the
reference "foo" and all the blocks under a subtree B of subtree A to
have the reference "bar", while also having the reference "foo".

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?

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)))))))
 		     (funcall expand-references id cache)))))
 	     ;; Interpose PREFIX between every line.
 	     (mapconcat #'identity

With this I already get interesting results. A noweb-ref "foo+bar" gets
expanded by <<foo>> by and <<bar>>. For example if I define references like
this

#+BEGIN_SRC emacs-lisp :noweb-ref one
aaa
#+END_SRC
#+BEGIN_SRC emacs-lisp :noweb-ref two
bbb
#+END_SRC
#+BEGIN_SRC emacs-lisp :noweb-ref one+two
ababab
#+END_SRC

and tangle them like this

#+BEGIN_SRC emacs-lisp :tangle one.el :noweb yes
<<one>>
#+END_SRC
#+BEGIN_SRC emacs-lisp :tangle two.el :noweb yes
<<two>>
#+END_SRC

I get two files
one.el:
aaa
ababab

and two.el:
bbb
ababab

This is already nice!
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?

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.

Best,

Théo

Re: Multiple noweb-ref

[Ihor Radchenko]

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>

Re: Multiple noweb-ref

[Théo Maxime Tyburn]

Hi Ihor,

>> 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.

Might be. So maybe we could use another non-alphabetical character? What
about "|" ?

>> 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'

I like the idea. Thanks for the hint, I'll try that out!

Best,

Théo

Re: Multiple noweb-ref

[Ihor Radchenko]

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

>> + 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.
>
> Might be. So maybe we could use another non-alphabetical character? What
> about "|" ?

I do not feel like being creative with characters here is a good idea.
I think that using multiple :noweb-ref+ will be more reliable and surely
will not break any existing configs.

-- 
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>