Question

While setting up autocomplete in Emacs irb (inferior-ruby-mode), I ran into a problem of not being able to add only Ruby mode buffers as AC sources. I can eg. add files in the current directory by

(setq ac-sources '(ac-source-files-in-current-dir))

or I can add all buffers (which I resorted to in the end) by

(setq ac-sources '(ac-source-words-in-all-buffer))

but what I would really like is to only add Ruby mode buffers. ^^

Answer 1

look to ac-source-words-in-same-mode-buffers… We can re-use this approach to build our own completion sources, for example:

 (ac-define-source words-in-ruby-buffers
   '((init . ac-update-word-index)
     (candidates . (ac-word-candidates
                     (lambda (buffer)
                       (eq (buffer-local-value 'major-mode buffer) 'ruby-mode))))))

will give us ac-source-words-in-ruby-buffers completion source.

P.S. I hadn’t tested it, but it should work 😉