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

[martin rudalics <rudalics@gmx.at>]

 >>(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.