How to make auto-complete work in AucTeX mode?

Question

I want auto-complete (ac) to work when I am inside AucTeX mode. I get all packages from MELPA by package installation.

This is my relevant code in init.el file:

(require 'package)
(package-initialize)
(require 'auto-complete-config)
(ac-config-default)   
(global-auto-complete-mode t)

as you can see, although I am setting ac globally it does not appear in AucTeX. However, by following instructions in this emacswiki, ac mode was displayed in status bar in AucTeX but non-functioning, no auto-completion by typing characters.

Notes
Emacs 24.4 under Windows 7 32bit and packages were updated.

Answer 1

After doing a long research in the web and careful examination of ac documentation with a lot of trials on my machine to examine code line by line, I came up with this solution that can have yasnippet working as well (optioinal) without any confict.

put this in your init.el or .emacs taking care of sequence:

(require 'package)
(package-initialize)

;; yasnippet code 'optional', before auto-complete
(require 'yasnippet)
(yas-global-mode 1)

;; auto-complete setup, sequence is important
(require 'auto-complete)
(add-to-list 'ac-modes 'latex-mode) ; beware of using 'LaTeX-mode instead
(require 'ac-math) ; package should be installed first 
(defun my-ac-latex-mode () ; add ac-sources for latex
   (setq ac-sources
         (append '(ac-source-math-unicode
           ac-source-math-latex
           ac-source-latex-commands)
                 ac-sources)))
(add-hook 'LaTeX-mode-hook 'my-ac-latex-mode)
(setq ac-math-unicode-in-math-p t)
(ac-flyspell-workaround) ; fixes a known bug of delay due to flyspell (if it is there)
(add-to-list 'ac-modes 'org-mode) ; auto-complete for org-mode (optional)
(require 'auto-complete-config) ; should be after add-to-list 'ac-modes and hooks
(ac-config-default)
(setq ac-auto-start nil)            ; if t starts ac at startup automatically
(setq ac-auto-show-menu t)
(global-auto-complete-mode t) 

Notes:
as mentioned in the documentation of ac, the adding to ac-modes and hooks should be done before loading (ac-config-default).

Some suggested to put some code to play with TAB key which I didn't need and do not recommend as it will somehow destroy something else later. However, I saw people put something like this at the end just before global-auto-complete:

(ac-set-trigger-key "TAB")
(ac-set-trigger-key "<tab>")  

Until I added (ac-flyspell-workaround) auto-completion was too slow to think of using it in Auctex since I use flyspell. This bug was also mentioned in the documentation. Thanks!

Bonus
I was glad to know from the documentation, though not very clear how, that one can add a user-defined dictionary(ies)! I tried this and worked well.

add these two lines just after require-auto-complete line above:

(add-to-list 'ac-dictionary-directories "~/.emacs.d/.dict") ; make sure this folder exists
(add-to-list 'ac-user-dictionary-files "~/.emacs.d/.dict/custom-dict.txt") ; put any name to your `.txt` file  

Now in your .txt file add your favorite candidates for completion. Save yourself from candidates fewer than 4-letter long, they don't worth it! Simply put words of your like separated by a line feed or RET.

Example of the contents in the .txt file:

inconsistencies
[email protected]
do-not-put-your-password-here
long-line-in-any-programming-language-of-your-like

Enjoy auto-completion in LaTeX/AUCTeX with Emacs!

Answer 2

As I told in my above comment, the package auto-complete-auctex can also solve the problem. I tested both, and they both work nicely. It would be nice to compare the solution of @doctorate and the above package by giving screen-shots. If I write $\sig$, the code of doctorate give something like this

and that of the package auto-complete-auctex gives something like this

Added: I should mention that the solution of @giordano works as well, here a screen-shot:

Answer 3

The following is my auto-complete related configuration:

(require 'package)
(package-initialize)
(require 'auto-complete-config)
(ac-config-default)

;; Activate auto-complete for latex modes (AUCTeX or Emacs' builtin one).
(add-to-list 'ac-modes 'latex-mode)

;; Activate ac-math.
(eval-after-load "latex"
  '(when (featurep 'auto-complete)
     ;; See https://github.com/vspinu/ac-math
     (require 'ac-math)
     (defun ac-latex-mode-setup ()       ; add ac-sources to default ac-sources
       (setq ac-sources
         (append '(ac-source-math-unicode ac-source-math-latex ac-source-latex-commands)
             ac-sources)))
     (add-hook 'LaTeX-mode-hook 'ac-latex-mode-setup)))

As you can see, there is nothing special for AUCTeX, it's the standard configuration of auto-complete. The configuration for ac-math is described on its web site. If you don't use ac-math, the only sensible difference with your configuration is (add-to-list 'ac-modes 'latex-mode).