How to remove "Toggling multi-web-mode off; better pass an explicit argument" message in Emacs?

Question

I have noticed, from a while, that every time I run emacs in multi-web-mode I get the following message:"Toggling multi-web-mode off; better pass an explicit argument".

Why do I get that? multi-web-mode is not toggled off because I use it and it works fine, but I keep getting this message all the time.

How can I fix this little trouble?

This is my code in my .emacs file where "multi-web-mode" appears (I am using Emacs 23.4):

(require 'multi-web-mode)
(setq mweb-default-major-mode 'html-mode)
(setq mweb-tags '((c++-mode "<\\?php\\|<\\? \\|<\\?=" "\\?>")
                  (ecmascript-mode "<script +\\(type=\"text/javascript\"\\|language=\"javascript\"\\)[^>]*>" "</script>")
                  (css-mode "<style +type=\"text/css\"[^>]*>" "</style>")))
(setq mweb-filename-extensions '("php" "htm" "html" "ctp" "phtml" "php4" "php5"))
(multi-web-global-mode 1)

(add-to-list 'auto-mode-alist '("\\.php\\'" . multi-web-mode))
(add-to-list 'auto-mode-alist '("\\.html\\'" . multi-web-mode))

Answer 1

Well it sounds like somewhere there's some code causing this mode to be called, non-interactively, with no arguments: (multi-web-mode). A common cause would be specifying a mode function symbol for use as a callback, rather than specifying a function which will call that mode function (with an argument).

This certainly used to be bad form, as it would indeed act as a toggle, just as it does in the interactive case (e.g. M-x multi-web-mode). Since Emacs 24, however, it is actually safe to do (at least for modes defined with the standard macros), as a non-interactive call with no argument to a mode function now always means 'enable'. This might account for the fact that you're not actually seeing a problem.

I don't think stock Emacs has ever generated such a message, so I would presume it's multi-web-mode itself which is detecting and reporting on this. It may need to be updated to reflect the change in Emacs 24. (Edit: looks like I was wrong about that; I guess Emacs 23.4 did produce this warning.)

Your simplest fix is probably to show us any lines from your config which mention multi-web-mode, so someone can show you how to change it to ensure that it passes an explicit argument (which is typically 1 to enable a mode).

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Edit: Okay, your problem is that multi-web-mode is a minor mode (as opposed to a major mode), but you have specified it in auto-mode-alist which is a mechanism for mapping filename patterns to major modes.

So the cause is exactly as I suggested above when I said "A common cause would be specifying a mode function symbol for use as a callback", as those auto-mode-alist entries will result in a call to (multi-web-mode).

It appears to me that multi-web-global-mode handles enabling the minor mode as required, so you just need to remove the bad auto-mode-alist entries.