bug#71364: Fix Table.el export

[Lockywolf Laptop]

Apologies for a delay. My life has been a little hectic recently.

While I have, indeed, contributed a bit to the table.el's support for
latex, I can't say that I am a big guru either on table.el or on latex.

I used table.el instead of native org tables because table.el supports
multiline cells, which I needed to write parallel texts in several
languages, naturally having different number of lines per passage.

So it is, indeed, "somewhat useful and working" for people not using
mathematics.

I have never tried writing latex code into table cells, and although I
agree that multiline tables might be useful with support for
mathematics, I also quite agree that making LaTeX work as expected is
hard, even when not using language-to-language transformations.

I can see why everything was escaped in the past, because it is the
easiest way to make sure that "everything at least compiles" even if the
result is not what one would expect naively.

(As a side-note, using the dollar signs in LaTeX mathematics is a bad
practice, because identical delimiters serving different roles when in
an even or odd position easily confuse the parser. Using \(\) and \[\]
is strongly preferred.)

>So it's a YES, because I was saying the same thing.

If you look at the const called table-source-languages, it should imply
that there "should" be export to languages other than LaTeX, but as
already mentioned, table--generate-source-scan-lines does not support
any language other than LaTeX, because nobody implemented, I guess.

>should or should not expect LaTeX markup

How much of LaTeX markup?
What if you add some mysterious \makeatletter there?

I generally agree with Reuben that making this work is a thing hard to
get right.

Moreover, as I mentioned above, I only used table.el with org-mode, but
I can't remember for sure what happens if one uses org-links in the
table.el cells. Do they become latex href links? Or links to images? Do
they turn into \includegraphics? Latex math is part of org, so I
presume, it is expected to somehow work, but I am not sure how.

>In any case, this is beyond the immediate issues discussed in this bug
>report, I think.  Broken code must be fixed.

I don't think it is a bug. It is an intentional limitation of scope,
which implements a crude but simple way of producing valid outputs,
albeit not 100% functional.

However I do not want to outright recommend rejection of the patch.
After all, implementing "simple math" is a valid desire for someone who
wants to print a table of integrals.

If I may, I would ask Mr Pranshu to spend a bit more work on this patch,
and do some straightforward, albeit a little tedious work to make this
patch more pleasant. May I?

1. Add a check to table--generate-source-scan-lines, which would
actually check that the variable _language equals to latex, and bail out
if it is not. Silently doing export to latex if html output is requested
is even worse than politely refusing.
2. Implement a defcustom table-el-cell-export-function-latex, which would be
called on each cell.
3. Implement a default value for this function, which should basically
amount to factoring out the code already in
table--generate-source-scan-lines. This way nothing will break.
This function maybe called table-el-cell-export-latex-default
3. Implement a copy of this function, with support for additional
escaping tricks needed by Mr Pranshu. It can be called
table-el-cell-export-latex. I do not think that a special defcustom
for the regexp is needed, because such export functions can be expected
to be written by people who need them necessarily in an ad-hoc way, and
customisations might not be well described by just a regexp.

It is a bit of work, but at least it will add some necessary extension
points. And org-mode, when exporting to table.el used in org files,
could override that cell export function to its own benefit.

(By the way, I haven't checked, but probably org-mode already has some
additional support for exporting table.el? I remember successfully
exporting org-files with table.el tables into html, which is seemingly
not supported in table.el itself.)

P.S.

Thank you Reuben for workign on ispell.el.
I think that Emacs would benefit from improved spellchecking, but I
myself didn't have time to explore it with sufficient assiduity.

Eli Zaretskii <eliz@gnu.org> writes:

> Ping!  Vladimir, could you please respond?
>
>> Cc: 71364@debbugs.gnu.org, rrt@sc3d.org
>> Date: Sat, 22 Jun 2024 12:39:58 +0300
>> From: Eli Zaretskii <eliz@gnu.org>
>> 
>> > From: Pranshu <pranshusharma366@gmail.com>
>> > Date: Fri, 21 Jun 2024 18:25:46 +1000
>> > Cc: rrt@sc3d.org, lockywolf@gmail.com, 71364@debbugs.gnu.org
>> > 
>> > How about now, it has been about 2 weeks
>> 
>> I'd like to hear from Vladimir as well.
>> 
>> Vladimir, would you please chime in and comment on this proposal?
>> 
>> 
>> 
>> 


-- 
Your sincerely,
Vladimir Nikishkin (MiEr, lockywolf)
(Laptop)

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