Re: [patch] ox-latex.el: Add `LATEX_PRE_HEADER' keyword

[Max Nikulin]

On 17/09/2023 01:00, Juan Manuel Macías wrote:
> [1] A longer example to export to a pdf that has pdf-x compliance, with
> the pdfx package:
>
> \providecommand{\pdfxopts}{x-1a}
> \begin{filecontents*}{\jobname.xmpdata}
>    \Title{Some Title}
>    \Author{Author}
>    \Language{es-ES}
>    \Keywords{keywords}
>    \Publisher{publisher}
> \end{filecontents*}
> \documentclass{...

Perhaps you have in mind other cases, but I am unsure concerning this 
one. However I have tried only setting metadata for hyperref only, so I 
may miss some important aspects.

First of all, I was unaware of .xmpdata and, trying to get more info, I 
have found hyperxmp that declares to reuse data from \hypersetup without 
extra files and without the requirement to add settings before 
\documentclass.

Do you need to add commands before \documentclass because you are using 
custom classes that loads a lot of packages, so there is no chance to 
specify various options after \documentclass, but before specific 
packages are loaded?

I do not think the lines above should be used directly in 
LATEX_PRE_HEADER. They should be generated from #+AUTHOR:, #+TITLE:, 
#+LANGUAGE: keywords. Have you considered the option to generate 
.xmpdata files directly from Org instead of delegating the task to LaTeX?

Another idea is to try export filter to insert content of a source block 
to the beginning of the export buffer. Unsure if it is convenient.