Re: export to latex without labels

[Eric Abrahamsen <eric@ericabrahamsen.net>]

Eric Abrahamsen <eric@ericabrahamsen.net> writes:

> "Salome "Södergran\"" <salome.soedergran@gmx.ch> writes:
>
>> Hello experts,
>>
>> I've been fiddling around for a while now with the following problem:
>>
>> When I export something from org to latex I get plenty of \labels that I never refer to. I'd like to get rid of all those labels.
>> I found some code [1] that uses a hook that does not work in orgmode anymore. So I tried to adapt that code to the new orgmode way with org-export-filter-final-functions:
>>
>> (defun ks/org-latex-remove-labels (backend info)
>>   "Remove labels generated by org-mode"
>>   (when (org-export-derived-backend-p backend 'latex)
>>   (let ((case-fold-search nil))
>>    (goto-char 1)
>>    (replace-regexp "\\\\label{sec-[0-9][^}]*}" "")
>>    )))
>>
>> (eval-after-load 'ox-latex
>>   '(add-to-list 'org-export-filter-final-output-functions
>>             'ks/org-latex-remove-labels))
>>
>>
>> When I now try to export something from org to latex, I get the following error message:
>>  Wrong number of arguments: (lambda (backend) "Remove labels generated by org-mode" (if (org-export-derived-backend-p backend (quote latex)) (progn (let ((case-fold-search nil)) (goto-char 1) (replace-regexp "\\\\label{sec-[0-9][^}]*}" ""))))), 3
>>
>> I am just an emacs user, not a programmer, and I have no idea what's wrong and what I have to change to make it work. Can anyone give me a hint?
>> TIA, Salome
>
> The error message is telling you that the wrong number of arguments were
> passed to your filter function. If you look at the doctoring of
> org-export-filter-final-output-functions, you'll see that functions in
> this filter are passed three arguments (note the 3 at the end of your
> error message), but your function only accepts two.
>
> Once you've sorted that out, you'll see that the argument you're missing
> is an argument representing the full exported string. That means that
> `replace-regexp' is probably the wrong function to be using inside your
> function. Actually, if you look at the docstring of replace-regexp, that
> was the wrong function to be using anyway :) It recommends using a
> combination of re-search-forward and replace-match in lisp functions.
>
> Since you've got a string, try replace-regexp-in-string instead! See the
> docstring...
>
> Lastly, it's possible that you could use a more narrowly-targeted filter
> for this particular case (rather than filter-final-output, which doesn't
> kick in until everything else is done). When exporting to latex, the
> element that turns into \label is a target, and that happens in
> org-latex-target. The corresponding filter is
> org-export-filter-target-functions, so you might consider putting your
> function in that variable instead. That could be much simpler: the
> function would take three arguments, the second of which is the backend,
> as a symbol. You could just check if the symbol was 'latex, and have the
> function return an empty string. The function body could be as simple
> as:
>
> (defun org-latex-remove-labels (string backend data)
>   (if (org-export-derived-backend-p backend 'latex)
>       ""
>     string))
>
> I haven't tested this for unexpected consequences, mind you...
>
> Really really lastly, does it really matter if there are unused \labels
> in the output?

Hmm, that might have been too much information. What I'm proposing is
just this:

(defun ks/org-latex-remove-labels (string backend info)
  "Remove labels generated by org-mode"
  (if (org-export-derived-backend-p backend 'latex)
      ""
    string))

(eval-after-load 'ox-latex
  '(add-to-list 'org-export-filter-target-functions
            'ks/org-latex-remove-labels))