Getting auto-complete to work correctly in scribble-mode

Question

I've been using Neil Van Dyke's scribble-mode for editing Scribble code in Emacs. I'm also using auto-complete and ac-capf to get better completion in scribble-mode. However, I've been running into a problem wherein I can't get auto-completion directly after an @ character in scribble-mode buffers. This is a problem because the @ character is an important part of Scribble's syntax. My current workaround is to type a keyword out and use a keybinding to auto-insert an @ before the word. However, this is becoming quite tedious and I would like to have normal-style completion instead. A very weird part about this is that pressing M-TAB (which runs the completion-at-point function) displays completion candidates in the *Completions* buffer, even after an @ character, so I'm not sure why this isn't working with auto-complete / ac-capf. Here's a screencast demonstrating my problem.

So, my question is how can I get auto-completion to work directly after an @ character in scribble-mode?

Answer 1

I came up with a hacky solution / workaround to this problem. Instead of using ac-capf for completion, I used ac-company to access the company-capf backend of company-mode. I put the following code in my init files to do this:

;; Feed company backends to auto-complete
(autoload 'ac-company-define-source "ac-company" nil nil 'macro)
(autoload 'ac-company-prefix "ac-company")
...
(ac-company-define-source ac-source-company-scribble company-capf)
(add-hook 'scribble-mode-hook '(lambda ()
                                 (add-to-list 'ac-sources 'ac-source-company-scribble)
                                 (auto-complete-mode t)))

The reasons that this is hacky are that 1) it doesn't address the issue with ac-capf 2) this solution borks the auto-complete menu faces and 3) this solution causes an annoying error to appear in the minibuffer on completion and when cycling through completion candidates: Error running timer ‘ac-quick-help’: (wrong-type-argument stringp nil). Nonetheless, the error and messed up faces seem to be of no consequence and this solution appears to work fine. Here's a screencast showing it in action.