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

[Max Nikulin]

On 27/09/2023 02:12, Juan Manuel Macías wrote:
> Max Nikulin writes:
>
> > I just have checked that a dirty hack with a few lines of code for
> > `org-export-filter-final-output-functions' allows to insert arbitrary
> > text to the beginning of export result. Perhaps a more elegant solution
> > exists, but I admit it is not a straightforward way. At least it is
> > possible.
>
> And it is also possible by simply defining a new class (in Org
> terminology, not LaTeX). My usual class is an almost empty one, without
> documentclass and without packages, because I don't want org to write
> the preamble for me. But I think this is not the point.

LATEX_PRE_HEADER you proposed is a document-local setting while 
`org-latex-classes' is shared by all Org documents. In that hack I used 
a buffer-local variable to achieve document-specific fragment.

In the specific cases of \DocumentMetadata and .xmpdata, 
LATEX_PRE_HEADER needs to be passed through `format-spec' with result of 
`org-latex--format-spec' call to get notion of Org metadata. Whether it 
is necessary for \PassOptionsToPackage depends on particular cases. If 
such options do not vary across documents then certainly 
`org-latex-classes' becomes viable.

I do not like "[NO-PACKAGES]" and similar keywords to suppress adding of 
some code snippets. That is why I believe it is better to seek for 
another approach to generate LaTeX preamble. I have not had a look into 
Timothy's code yet, so I can say nothing concerning its flexibility in 
respect to substituting metadata into code before \documentclass.