Re: [Dev-luatex] LuaTeX doesn't discard empty paragraphs when textdir is used

29 Jul 2021


      On 7/29/2021 9:54 AM, luigi scarso wrote:
...
On Mon, Jun 21, 2021 at 5:03 PM Marcel Krüger mailto:tex@2krueger.de> wrote:
Hi,
consider the following plain LuaTeX document:
\textdir TRT
    \noindent\par
    \bye
without the `\textdir TRT` line or with `\textdir TLT`, this would lead
    to "warning  (pdf backend): no pages of output.", but with the non
    default "\textdir", it creates an empty (except for the page number)
    page
    instead.
This can be avoided by setting \pardir too:
\textdir TRT\pardir TRT
    \noindent\par
    \bye
again produces no output, but adding a group around it reintroduces the
    issue:
\begingroup
    \textdir TRT\pardir TRT
    \noindent\par
    \endgroup
    \bye
leads to an empty page.
Of course similar things happen not only for otherwise empty documents:
    Instead of empty paragraphs disappearing, they add empty lines.
Together, this is not only inconsistent with other engines which always
    discard empty paragraphs, but also leads to hard to predict behavior
    (especially for users who are not familiar with the implementation of
    LuaTeX's directional system), so I think it would be great if LuaTeX
    could always remove such empty paragraphs.
(sorry for the delay)
Do you have  a patch to propose  ?
it's a side effect of the direction handler picking up states ... kind 
of tricky code but i can probably come up with a fix (maybe under 
parameter control)

(of course normally a macro package will catch these kind of things if 
needed)

Hans


-----------------------------------------------------------------
                                           Hans Hagen | PRAGMA ADE
               Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
        tel: 038 477 53 69 | www.pragma-ade.nl | www.pragma-pod.nl
-----------------------------------------------------------------