Is there a way to avoid appending AUCTeX variables in the file when working with multiple files?

Question

When editing multiple files, AucTeX keeps track of the master file by appending the following to each file:

%%% Local Variables:
%%% mode: latex
%%% TeX-master: "../document"
%%% End:

I'm editing a document with multiple colleagues and I don't want to add this to their files when editing them.

Is there a way to set an AucTeX variable pointing to the path of the master file, and whenever I hit C-c C-c, it will look for that file?

One option is to hit M-: and type (setq-default TeX-master "../document"). Is there a better way than that?

Answer 1

Not sure what AUCTeX does when TeX-master is not set, nowadays, but if you use the default latex-mode that comes with Emacs, the corresponding tex-master is guessed by looking for a nearby buffer with the usual \documentclass thingy. If you keep one document per directory, this is usually all it takes to DTRT and you don't need to set any file-local variable: just make sure you have that main .tex file opened in a buffer in that same Emacs session.

AUCTeX being usually fancier than this builtin latex-mode, I expect it also has some way to guess the right TeX-master. If it doesn't, then I suggest you file a feature-request.

But there are other options:

• Set the TeX-master from a .dir-locals.el file. To set up a .dir-locals.el file, the best way is through Emacs using M-x add-dir-local-variable.

• Set the TeX-master via dir-locals-set-class-variables and dir-locals-set-directory-class.

• Do you all by hand, old-school style:

  (add-hook 'LaTeX-mode-hook
            (lambda ()
              (when (string-prefix-p "/thing/with/colleagues"
                                     default-directory)
                (setq TeX-master "../document"))))