AUCTeX set LaTeX-default-tabular-environment back to "tabular"

Question

When I use the package tabularx in a tex file, if I insert table environment, the inner environment will be given as tabularx instead of tabular when the package tabularx is not used.

Normally this would not be a problem for me because I do not deliberately use the package tabularx. However, when I use \documentclasss{memoir}, the package tabularx is automatically used.

I found the variable LaTeX-default-tabular-environment and want to reset its value back to tabular (now I'm not sure it's the correct variable for me to reset),

(eval-after-load 'latex 
    (setq LaTeX-default-tabular-environment "tabular"))

but it does not work, and when I query the value for LaTeX-default-tabular-environment using C-h v, I get the following,

LaTeX-default-tabular-environment is a variable defined in `latex.el'. Its value is "tabularx"

Local in buffer test-tabularx.tex; global value is "tabular"

Automatically becomes buffer-local when set.

Now I am utterly confused. I also tried add some style hook, but it seems to me that I need to alter or update some hook instead just adding it. Could someone help me please? Thanks a lot!

---

After I put the code by Arash Esbati in my .emacs file, I noticed the following: even if I do not mention memoir in the tex file, for example

\documentclass{article}
\usepackage{tabularx}

\begin{document}
(cursor here)
\end{document}

if I then type C-c C-e table RET(a bunch of them), then I would get tabular inside table instead of tabularx inside table. Of course, I later realized that I had another tex file with \documentclass{memoir} loaded in emacs. If I kill that buffer and reboot emacs, everything will be as expected.

Answer 1

LaTeX-default-tabular-environment is the variable you want to reset. The hook you are looking for is TeX-update-style-hook:

Documentation: Hook run as soon as style specific hooks were applied.

You can use something like this in your init file:

(eval-after-load "memoir"
  '(add-hook 'TeX-update-style-hook
             (lambda () (setq LaTeX-default-tabular-environment "tabular"))))

---

AUCTeX style files try to follow the same logic as LaTeX packages regarding loading other packages. AUCTeX has a function TeX-run-style-hooks which is comparable to LaTeX's \RequirePackage macro. I presume that you have this in your .emacs:

(setq TeX-parse-self t)

Now when you load a .tex file like this:

\documentclass{memoir}
\begin{document}
(cursor here)
\end{document}

AUCTeX loads the file memoir.el which contains the following line:

(TeX-run-style-hooks "tabularx")

and next it loads the file tabularx.el containing:

(setq LaTeX-default-tabular-environment "tabularx")

When you have a .tex file like this:

\documentclass{article}
\usepackage{tabularx}
\begin{document}
(cursor here)
\end{document}

AUCTeX loads the file tabularx.el directly.

In general, all these changes should be local to the buffer you're working in, other .tex buffers should not be affected.