Re: Re: [BUG] beamer export

[Pedro Andres Aranda Gutierrez]

Hi

CAVEAT EMPTOR: Although it’s some years that I have been using org to create my slides, I never needed this… Interesting to learn new things ;-) 

I personally would not oppose to have a customizable org-frame-environment variable, with its default value being “frame”. 

Then, when actually emitting the code, add something like:

(unless (string= org-frame-environment “frame”

 …)

Which would create the code most of us would expect (i.e. \begin{frame}…\end{frame}) in almost any case except when you really need the `newenvironment’ construct.

My .02 cents, /PA

El 27 ene 2024, a las 18:00, emacs-orgmode-request@gnu.org escribió:

Message: 2
Date: Fri, 26 Jan 2024 20:54:17 +0000
From: Leo Butler <Leo.Butler@umanitoba.ca>
To: Ihor Radchenko <yantar92@posteo.net>
Cc: Ihor Radchenko <yantar92@gmail.com>, Daniel Fleischer
<danflscr@gmail.com>, Org Mode Mailing List <emacs-orgmode@gnu.org>
Subject: Re: [BUG] beamer export
Message-ID: <87wmrvlsso.fsf@t14.reltub.ca" style="font-family: Helvetica; font-size: 14px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px;" class="">87wmrvlsso.fsf@t14.reltub.ca>
Content-Type: text/plain; charset="iso-8859-1"

On Fri, Jan 26 2024, Ihor Radchenko <yantar92@posteo.net> wrote:

Leo Butler <Leo.Butler@umanitoba.ca> writes:

Apparently, LaTeX has really hard time processing verbatim code inside
beamer frames.

I looked again at the solution here:
https://tex.stackexchange.com/questions/140719/verbatim-in-beamer-showing-error-file-ended-while-scanning-use-of-xverbatim

and it errors out with a recent version of pdflatex:

  This is pdfTeX, Version 3.141592653-2.6-1.40.25 (TeX Live 2023/Debian) (preloaded format=pdflatex)

This is, apparently, a known problem:

https://github.com/josephwright/beamer/issues/360

The end of that issue report includes a work-around that we might apply
in org. I have attached a patch for your feedback. The example that
stimulated this discussion compiles with the patch and the testsuite
shows no errors related to it.

Thanks!
I have concerns about your approach though.

You are replacing all the frame environments with custom environment
unconditionally. However, custom environment has downsides. For example,
\againframe will stop working, as pointed earlier in the linked beamer
thread
https://github.com/josephwright/beamer/issues/360#issuecomment-708705250

The comment that you are citing shows how to define the custom
environment so that \againframe works correctly. See the attachment
`beamer-example-againframe.tex' and pdf. You can see that \againframe
works with the custom environment.

Since the problem appears only when the frame contents contains
\end{frame}, it may be sufficient to replace the standard frame
environment with the workaround only in such scenario.

Yes, that might be true. But my feeling is that it would be simpler and
more robust to use the custom frame environment in most cases.

+;; Needed to set-up Beamer export.
+(defconst org-beamer--frame-environment
+  (concat "orgframe" (org-id-uuid))
+  "Name of the beamer frame environment.
+This is randomized to prevent collisions.")

Please use constant name. (org-id-uuid) makes export randomized for no
good reason.

There is a good reason to randomize (or at least make customize-able)
the environment name: so that beamer code generated by ox-beamer can be
safely inserted into org files and exported by ox-beamer. With a fixed
name for the environment, we will have just recreated the original
source of the bug report. As a compromise, in the attached patch, I have
made the environment name customize-able.

;; Install a default set-up for Beamer export.
(unless (assoc "beamer" org-latex-classes)
  (add-to-list 'org-latex-classes
-        '("beamer"
-  "\\documentclass[presentation]{beamer}"
+        `("beamer"
+  ,(concat "\\documentclass[presentation]{beamer}\n"
+                          ;; Define an alias for the beamer frame environment
+                         "\\newenvironment<>{"
+                         org-beamer--frame-environment
+                         "}[1][]{\\begin{frame}[environment="
+                         org-beamer--frame-environment
+                         ",#1]}{\\end{frame}}")

Please use `org-beamer-template' rather than modifying the class.
Modifying the class may confuse users.

Ok, I have done so.

The docstring of `org-latex-classes' says:

   The HEADER-STRING is the header that will be inserted into the
   LaTeX file.  It should contain the \documentclass macro, and
   anything else that is needed for this setup.

From that, I figured that would be the correct place to put that

\newenvironment command. I have moved it, as requested.

Please see the revised patch. I believe that I have taken into account
your suggestions.

Leo