Preferring certain file extensions with Emacs file name completion

Question

I have lots of directories filled with a bunch of TeX documents. So, there's lots of files with the same base filename and different extensions. Only one of them, though, is editable. I'd like a way to convince Emacs that if I'm in a directory where I've got

document.tex
document.log
document.pdf
document.bbl
document.aux
...

and I'm in the minibuffer and do

~/Documents/.../doc<TAB>

it fills in 'document.tex', because that's the only really properly editable document in that directory. Anybody know of a good way to do that?

Answer 1

Probably the easiest way to do this in your case is just to customize the variable "completion-ignored-extensions".

However, this will mean that emacs always ignores things like ".log" and ".pdf" which may not be what you want. If you want it to be more selective, you may have to effectively re-implement the function file-name-completion.

Answer 2

If you are open to installing a large-ish library and reading some documentation, you could take a look at Icicles and define a sort function that meets your needs. An alternative is ido whose wiki page has an example of sorting by mtime, which should be easy to change to sort by a function of the filename extension.

Answer 3

I've written some code that should do what you want. The basic idea is to set the variable 'completion-ignored-extensions to match the extensions you want to skip, but only when there are .tex files present. This code does that.

(defadvice find-file-read-args (around find-file-read-args-limit-choices activate)
  "set some stuff up for controlling extensions when tab completing"
  (let ((completion-ignored-extensions completion-ignored-extensions)
        (find-file-limit-choices t))
    ad-do-it))

(defadvice minibuffer-complete (around minibuffer-complete-limit-choices nil activate)
  "When in find-file, check for files of extension .tex, and if they're found, ignore .log .pdf .bbl .aux"
  (let ((add-or-remove
     (if (and (boundp 'find-file-limit-choices) find-file-limit-choices
       (save-excursion
  (let ((b (progn (beginning-of-line) (point)))
        (e (progn (end-of-line) (point))))
    (directory-files (file-name-directory (buffer-substring-no-properties b e)) nil "\\.tex$"))))
  'add-to-list
       'remove)))
(mapc (lambda (e) (setq completion-ignored-extensions
   (funcall add-or-remove 'completion-ignored-extensions e)))
      '(".log" ".pdf" ".bbl" ".aux")))
  ad-do-it)

Enjoy.