Re: [O] org-latex-classes with functions, incomplete doc

[Nicolas Goaziou]

Hello,

Florian Beck <address@hidden> writes:

> the docstring for `org-latex-classes' says:
>
> "Instead of a list of sectioning commands, you can also specify
> a function name.  That function will be called with two
> parameters, the (reduced) level of the headline, and a predicate
> non-nil when the headline should be numbered.  It must return
> a format string in which the section title will be added."
>
> This is wrong. The way this function is called in `org-latex-headline'
> requires it to return a string with TWO format specifiers, e.g.
> "\section{%%s}%%s\n", the second where the CONTENT of the section is
> being added. Maybe `org-latex-headline' should add "%%s\n" itself – as
> it does for other cases?

Indeed. It's now the case. Thanks for reporting this.

> Also, I'm using this to add an optional argument to my sections. Can I
> expect this to work? (i.e. being called in a context where the variables
> `info' and `headline' are defined?)
>
> #+BEGIN_SRC emacs-lisp
> (defun fb/latex-sections (level numbered)
>     (let* ((level (1- level))
>            (sec-name (nth level fb/latex-section-names))
>            (sec (when sec-name
>                   (format "\\%s%s%s{%%s}\n%%s"
>                           sec-name
>                           (if numbered "" "*")
>                           ;; ""
>                           (or (when (plist-get info :toc-title)
>                                 (let ((toc-title (org-element-property 
> :toc-title headline)))
>                                   (when toc-title (format "[%s]" toc-title))))
>                                    "")
>                           ))))
>       sec))
> #+END_SRC

Actually, the proper way to do this is to define a derived back-end with
a custom headline translation function.

#+begin_src emacs-lisp
(org-export-define-derived-backend my-latex latex
  :translate-alist ((headline . fb/my-latex-headline)))

(defun fb/my-latex-headline (headline contents info)
  ...
  Do whatever you want here)
#+end_src

Also, you can use `org-export-with-backend' as a fallback case for your
custom function.

>From there you can use:

  (org-export-to-buffer 'my-latex "*My own export*")

or,

  (org-export-to-file 'my-latex "some-file.tex")

You may wrap the previous calls into an interactive command (just copy
and adapt from those in ox-latex.el). For example:

#+begin_src emacs-lisp
(defun fb/my-latex-export-to-latex
  (&optional async subtreep visible-only body-only ext-plist)
  (interactive)
  (let ((outfile (org-export-output-file-name ".tex" subtreep)))
    (if async
        (org-export-async-start
            (lambda (f) (org-export-add-to-stack f 'my-latex))
          `(expand-file-name
            (org-export-to-file
             'my-latex ,outfile ,subtreep ,visible-only ,body-only 
',ext-plist)))
      (org-export-to-file
       'my-latex outfile subtreep visible-only body-only ext-plist))))
#+end_src

Optionally, you can add an entry in the dispatcher for your new command:

#+begin_src emacs-lisp
(org-export-define-derived-backend my-latex latex
  :translate-alist ((headline . fb/my-latex-headline))
  :menu-entry
  (?l 2 ((?m "With my special extension" fb/my-latex-export-to-latex))))
#+end_src


Regards,

-- 
Nicolas Goaziou