Re: Differencing a major mode from its derived modes

[Kai Grossjohann <kai@emptydomain.de>]

chem <chemtov@ifrance.com> writes:

>> I forget whether testing the variable major-mode was already
>> mentioned.  You could write a function that checks (eq major-mode
>> 'text-mode), and only if this is true, then activate allout mode.
>
> yes, i tried that, but it only work if the mode is not derived from
> text-mode (eg. LaTeX - from aucTeX), but not if it is (eg. message).
> In the latter, code like this one :
>
> (add-hook 'text-mode-hook
>           '(lambda ()
>               (if (eq major-mode 'text-mode)
>                   (flyspell-mode 1)
>                 (turn-on-auto-fill))))
>
> will run the THEN _and_ the ELSE part of the IF expression, while in
> the former, only then ELSE part is evaluated.

I think that's because text-mode-hook is run twice: once as part of
message-mode, and once more because message-mode is derived from
text-mode.

IMHO this should not happen: text-mode-hook should be run only once
in this case.

I wonder if this is really a bug, and if so, how to fix it.

> Furthermore, something like :
>
> (derived-mode-p 'text-mode)
>
> will return true even in text-mode (while it's hardly derived from
> text-mode, isn't it?).

Hm.

> So, I found no easy way to discriminate between parent from derived
> children mode.  
>
> Thanks again for the support.
>
> PS: Could you tell me if receive my reply twice : on the mailing list
> (or the newsgroup) and in your mailbox.  I'm curious to know if all
> (of my gnus and message configurations) is working as intended.

I got it twice.  I deleted the mail.

But note that the mail reply was addressed to help-gnu-emacs, not to
a newsgroup.  Not sure if that is relevant.

Kai