Re: [PATCH] Allow tangling to a list of files

[Vladimir Lomov]

Hello Jacopo.
** Jacopo De Simoi <wilderjds@protonmail.com> [2021-07-06 11:24:40 -0400]:

> Dear Vladimir, 

>  thanks for your reply.

> Let me show you two examples; they are both WIP and incomplete, but you'll 
> get 
> the gist. 

> - Example 1

> https://gist.github.com/85c9b9c9ab151c5fd35bd761ef6ef569

> This is my literate config for .zshrc; as you can see different blocks are
> tangled to different set of files; hence the output files differ (as some
> blocks are present and other are not) 

I couldn't find in Org manual how tangling should work if there are several
source code blocks with the same file name for ':tangle'. The Org manual
section "15.8 Extracting Source Code" is a bit obscure. There are these two
sentences

  When Org tangles code blocks, it expands, merges, and transforms
  them.  Then Org recomposes them into one or more separate files, as
  configured through the options.

The second sentence assumes that it might be possible to tangle to more than
one file but possible options for ':tangle' don't give certain answer:

  yes’

       Export the code block to source file.  The file name for the source
       file is derived from the name of the Org file, and the file extension
       is derived from the source code language identifier.
       Example: ‘:tangle yes’.

  FILENAME

       Export the code block to source file whose file name is derived from
       any string passed to the ‘tangle’ header argument.  Org derives the
       file name as being relative to the directory of the Org file’s
       location.  Example: ‘:tangle FILENAME’.

If I understand first choice correctly then the only source block ("the code
block") will be tangled (exported) to a source file. What Org will do if there
are several source blocks? Concatenate them or write to a file only last one?
(I didn't test that).

The same applies to 'FILENAME' case: what Org will do if there are several
source code blocks with the same 'FILENAME' for ':tangle'.

I would say that you use here undocumented feature and you workflow could be
broken if in some future Org version developers decide to implement only
documented features.

> - Example 2

> https://gist.github.com/2bce5d6df3f04c934fb4beda0c6560ad

> This is my literate config for xkb maps; I have several keyboards, and some 
> of 
> them require slightly different maps.

> Once again, likely all this can be accomplished by some noweb magic, but I 
> find 
> my approach much less intrusive (particularly the initial bit in the .zshrc, 
> which I am still refactoring, where the list of tangle targets is inferred 
> from the headline tags)

I found you way of doing things a bit strange. As I already told I use 'noweb'
feature a lot. I won't advise you to use it or not to use it but I find it
very powerful.

> Thanks again for your comments. I'd really like to see how to do the same
> with noweb and compare my approach with the "standard" one. Once more, I
> hope these examples clarify my point of view. 

If you don't distract by foreign language (Russian) you could look how I use
'noweb' feature for scripts (one example):

https://git.sr.ht/~vp1981/scripts/tree/master/item/docs/scripts/misc.org

for shell configurations:

https://git.sr.ht/~vp1981/scripts/tree/master/item/docs/shell/bash.org

and for Emacs configuration:

https://git.sr.ht/~vp1981/scripts/tree/master/item/docs/emacs/emacs.org

> Best 
>  Jacopo

[...]

---
WBR, Vladimir Lomov

-- 
str->str_pok |= SP_FBM;                     /* deep magic */
s = (unsigned char*)(str->str_ptr);         /* deeper magic */
                -- Larry Wall in util.c from the perl source code

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