Re: define-derived-mode runs parent mode hook after evaluating body

[martin rudalics]

>>(define-derived-mode change-log-mode text-mode "Change Log"
>>  "..."
>>  (setq left-margin 8
>>        fill-column 74
>>        ...
>
>
>>...but in my .emacs I have:
>
>
>>(add-hook
>> 'text-mode-hook
>> '(lambda () (setq fill-column 72)))
>
>
> The problem here is that we use text-mode both as a parent and as a real
> major-mode, so you can't change "text-mode" without changing all
> its derivatives.
>
> Maybe the real text-mode should be renamed to plain-text-mode (and derive
>>from text-mode, of course).

Which would solve this special case.  In general, however, I want to add
something to a parent-mode hook and pass it on to its derivatives unless
the derivatives have their own opinion about that.  Well, I could do

(add-hook
 'text-mode-hook
 '(lambda ()
    (unless (and (local-variable-p 'fill-column)
                 (not (equal fill-column
                             (default-value 'fill-column))))
      (setq fill-column 72))))

but this strikes me as inconvenient, ugly, and maybe faulty.