Re: [possible patch] Remove the '\\[0pt]' string from the last line of a verse block in LaTeX export

[Ihor Radchenko]

Juan Manuel Macías <maciaschain@posteo.net> writes:

>> May it be better to use something like
>>
>> \newcommand\nothing{}
>> \newcommand{\safenewline}{\\\nothing}
>>
>> And then use \safenewline instead of \\[0pt]
>>
>> In my tests,
>>
>> \begin{center}
>> \begin{tabular}{ll}
>> [t] & s\safenewline
>> [I] & A\safenewline
>> [m] & kg\safenewline
>> \end{tabular}
>> \end{center}
>>
>> Does not suffer from misinterpreting new line as argument.
>
> I remember the thread where these issues were discussed and the long
> discussion where many alternatives were proposed. After all, the \\[0pt]
> solution still seems the safest to me. It seems that the problem is
> located only in the verse environment, probably due to some particular
> redefinition of the \\ macro that makes that environment.

We chose \\[0pt] simply because we did not find anything better.
In fact, Max expressed some concerns about \\[0pt] - in
https://list.orgmode.org/orgmode/tik0uf$td1$1@ciao.gmane.io/ and
https://list.orgmode.org/orgmode/tio0th$vn8$1@ciao.gmane.io/

If the idea with custom command does not have obvious downsides, it
might be a better option. In the previous thread, we only considered
redefining \\ itself - obviously a non-starter for environments that
re-define \\ by their own, like here.

> In any case, square brackets are a problematic character in LaTeX
> (think, e.g., of some environment that takes an optional argument). I
> think pandoc chooses to always export them as {[}{]}:
>
> #+begin_src sh :results latex
> str="[hello world] [foo] [bar]"
> pandoc -f org -t latex <<< $str
> #+end_src
>
> #+RESULTS:
> #+begin_export latex
> {[}hello world{]} {[}foo{]} {[}bar{]}
> #+end_export
>
> We could do the same, but I'm afraid it's too late if
> org-latex-line-break-safe already exists... I don't remember if
> something similar was proposed in that discussion, and it was rejected
> for some reason.

It is not too late.

AFAIR, we just decided not to dig deeper about pandoc's approach.

As for {[}{]}, it is a bit difficult to implement. Especially when we
also consider user filters and derived backends. If we have several
transcoders of consequent elements, there is always a risk that even
when a given filter/transcoder is generating a valid LaTeX code,
concatenating them may still cause issues like we have with \\.

I am wondering if there are other examples of commands with optional
arguments that may cause a similar problem with

\command
[unrelated text]

If there are, we may actually want to consider pandoc's approach
seriously.

>> We may as well strip the trailing \\[0pt] there.
>
> I think it would be best to remove the last \\[0pt] in the verse block.
> I can prepare a patch, but I'm afraid that org-latex-verse-block is
> becoming an homage to replace-regexp-in-string...

Not a big deal. Or, if you want, you can make changes via temporary
buffer; if that is cleaner.

-- 
Ihor Radchenko // yantar92,
Org mode contributor,
Learn more about Org mode at <https://orgmode.org/>.
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