Juan Manuel Macías <maciasch...@posteo.net> writes:
>>> If I'm not mistaken, in TeX '\\' can only be used in horizontal mode:
>>> that is, within a paragraph. At the end of an environment like verse
>>> (\end{verse}) you are forced to enter vertical mode, and a new paragraph
>>> starts.
>>
>> Is it true for any environment? Or just some?
>
> In principle, nothing prevents one from defining an environment for use
> in horizontal mode (within the paragraph). E.g.:
> ...
> But the usual thing is that the beginning/end of an environment changes to
> vertical mode, with \par or something more elaborate.
This is annoying.
ox-latex has some transcoders that unconditionally add \\ at the
end: clocks and planning lines. If they happen to be at the end of an
environment, it can be problematic.
> hmm... I don't know if this should be considered a bug. We may think
> that \\[0pt] should never do anything, but we must keep in mind that the
> end of the verse environment is the end of a paragraph, and it changes
> to vertical mode. And the end of a paragraph is an illogical place to
> put that command. But it seems that it also alters things when it is at
> that point. Check out this reply from David Carlisle
> (https://tex.stackexchange.com/a/82666):
The very reason we use \\[0pt] is because it supposed to prevent
interpreting [...] at the new line/transcoded element as argument.
You demonstrated that it is yet not always safe enough.
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.
> If there are environments that redefine \\, such as verse or tabular,
> probably putting the optional argument of \\ with a value of 0pt at the
> end of verse alters the calculation of the normal space after the
> environment, making it shorter. I think that here we would not have a
> LaTeX bug, because the syntax of the verse environment itself says that
> the last line should not carry any \\ mark.
AFAIU, \safenewline should still use re-defined version of \\ according
to the context.
> At the end of the tables I have not noticed any side effects. But in the
> export of the verse block, I would be in favor of somehow eliminating
> that last \\[0pt].
`org-latex-verse-block' already has a giant regexp replacement:
;; In a verse environment, add a line break to each newline
;; character and change each white space at beginning of a line
;; into a normal space, calculated with `\fontdimen2\font'. One
;; or more blank lines between lines are exported as a single
;; blank line. If the `:lines' attribute is used, the last
;; verse of each stanza ends with the string `\\!', according to
;; the syntax of the `verse' package. The separation between
;; stanzas can be controlled with the length `\stanzaskip', of
;; the aforementioned package. If the `:literal' attribute is
;; used, all blank lines are preserved and exported as
;; `\vspace*{\baselineskip}', including the blank lines before
;; or after CONTENTS.
We may as well strip the trailing \\[0pt] there.
--
Ihor Radchenko // yantar92,
Org mode contributor,
Learn more about Org mode at <https://orgmode.org/>.
Support Org development at <https://liberapay.com/org-mode>,
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