bug#16759: CC Mode modes: mode hooks are called twice.

bug#16759: CC Mode modes: mode hooks are called twice.

[Alan Mackenzie]

In C Mode, etc., c-mode-hook, etc. gets called twice at mode
initialisation.  This is bad, since there will be, at least occasionally,
mode hooks which must not be called twice.

The cause of this is that there is an invocation of run-mode-hooks
generated by the macro define-derived-mode as well as an explicit call to
run-mode-hooks which is not at the end of the mode function.

-- 
Alan Mackenzie (Nuremberg, Germany).

bug#16759: CC Mode modes: mode hooks are called twice.

[Glenn Morris]

Alan Mackenzie wrote:

> The cause of this is that there is an invocation of run-mode-hooks
> generated by the macro define-derived-mode as well as an explicit call to
> run-mode-hooks which is not at the end of the mode function.

IIUC, this is because you want to run some C-mode stuff after the hooks.
A simple solution would be to add :after-hook to define-derived-mode.
You already did this for define-minor-mode.
It would be good for symmetry/consistency if nothing else, and seems
pre-approved:

http://lists.gnu.org/archive/html/emacs-devel/2012-02/msg00140.html

:)

bug#16759: CC Mode modes: mode hooks are called twice.

[Stefan Monnier]

>> The cause of this is that there is an invocation of run-mode-hooks
>> generated by the macro define-derived-mode as well as an explicit call to
>> run-mode-hooks which is not at the end of the mode function.
> IIUC, this is because you want to run some C-mode stuff after the hooks.

More specifically, it's always c-update-modeline, AFAICT.
A good solution would be to get rid of it and use something like

  (let ((lighters '("/" (c-electric-flag "l")
                        (c-electric-flag (c-auto-newline "a"))
                        (c-hungry-delete-key "h")
                        (subword-mode "w"))))
    (setq c-mode-options-format
          `(c-electric-flag ,lighters
            (c-hungry-delete-key ,lighters)
             (subword-mode ,lighters)))
    (cond
     ((memq 'c-mode-options-format mode-line-process) nil)
     ((equal "" (car-safe mode-line-process))
      (push 'c-mode-options-format (cdr mode-line-process)))
     (t (setq mode-line-process
              `("" c-mode-options-format ,mode-line-process)))))

> A simple solution would be to add :after-hook to define-derived-mode.
> You already did this for define-minor-mode.
> It would be good for symmetry/consistency if nothing else, and seems
> pre-approved:

I wouldn't say pre-approved.  But, yes, I guess it'd be OK.


        Stefan

bug#16759: CC Mode modes: mode hooks are called twice.

[Glenn Morris]

Stefan Monnier wrote:

>                         (subword-mode "w"))))

BTW, since subword-mode is now a generic minor mode with its own lighter,
I don't believe that cc-mode needs to report its status at all.

bug#16759: CC Mode modes: mode hooks are called twice.

[Stefan]

> IIUC, this is because you want to run some C-mode stuff after the hooks.

Note that "after the hooks" also means "after the code of the child
mode" if someone defines a child mode (since hooks get delayed to
after the child mode's code).

The need to "run things after the hooks" is not frequent but is not
exceptional either, so we should provide a good solution for it.
So far, the best solution I know is to use hack-local-variables-hook,
but that is not run if you use M-x c-mode RET.


        Stefan

bug#16759: CC Mode modes: mode hooks are called twice.

[Alan Mackenzie]

Bug fixed in the master branch.

-- 
Alan Mackenzie (Nuremberg, Germany).