Re: Line breaks and brackets in LaTeX export

[Max Nikulin]

On 17/10/2022 22:01, Juan Manuel Macías wrote:
> \documentclass{article}
> \usepackage{tabularray}

LaTeX I have installed is too old for this package. It is marked as 
"Experimental LaTeX3", so I am unsure, maybe you have found a bug in 
this package.
https://ctan.org/pkg/tabularray

You believe that an issue with brackets is extremely rare. It may be 
true for humanitarian texts. For some users it may be a constant source 
of pain e.g. in the case of interval notation as [a,b]. I have already 
mentioned tables generated by code blocks, not typed directly. I can not 
say that I often need to export my notes, but I was afraid that I will 
be bitten by this bug because I may try to put dates close to left margin:

- Something\\
  [2022-10-17 Mon]

By default dates wrapped into \textit, but it may be customized to just 
"%s".

Selectively adding some workaround require complete reimplementation of 
exporters. I have some curiosity concerning pandoc approach, but I am 
unsure if I will reserve some time to read its code.

An idea how to avoid complete redesign: at first add something like
   %__ORG_PROTECT_NEWLINE__
after each \\, later at an optimizing pass remove the comment if next 
line does not start from a star or a square bracket, otherwise use some 
workaround, e.g. "{[}". \relax may be suitable as well (in the beginning 
of rows, not after \\).

I do not like approach with a custom command. It is effectively the same 
as adding \empty but \\ may be redefined by some packages, so I strongly 
prefer to keep \\ in exported markup. Redefining of \\ is a way to new 
issues. I do not feel firm ground with a command that will expand to \\. 
I am afraid that \\ may still consume following "[" unless \empty or its 
equivalent is added after it. I am completely unsure concerning 
tabularray parser that does not rely on TeX primitives.

I found \empty when I was looking for an approach with minimal overhead. 
I expect that e.g. \\[0pt] may have higher performance penalty since it 
is expanded to several commands. When the idea with "\\\relax" failed I 
was choosing between "\\{}" and "\\\empty". I decided that the latter 
minimizes risk to add spurious space.

Some problems:

I do not see a way to add some LaTeX code between table lines.

Semi-verbatim environment may be a source of new bugs. They may be 
rather selective in respect to what they consider a command and what is 
passed as raw text. tabularray perhaps is similar in this sense.