Re: Feature request: permanent-local values in hooks buffer local values

[Lennart Borgman (gmail)]

Lennart Borgman (gmail) wrote:
> Richard Stallman wrote:
> >     Then in `flymake-mode' a call to the functions
> >     `flymake-add-survivor' and `flymake-remove-survivor \(which was 
> > defined     by the macro called above) must be done.
> >
> > This seems like a very cumbersome interface.  I think it is very
> > unclean to dynamically change `permanent-local' properties.  That's
> > the sort of thing that we are sure to regret.
> >
> > We should use my mechanism instead.  It is simple and clean.
>
> That is very fine with me.
>
> I suggest then adding something like this to the end of add-hook:
>
>     (when (and local
>                (get function 'permanent-local-in-hooks))
>       (put hook 'permanent-local-hook t)
>
> Then in kill-local-variables check for the property 
> 'permanent-local-hook and handle the hook accordingly.
>
> I can see no reasonable way to remove the property 'permanent-local-hook 
> from the hook variable. (The problem is that properties do not have 
> buffer local values. It could be simulated by having a buffer local 
> variable carrying the propery, but I see no reason to make it that 
> complicated.)

    (when (and local
               (and (symbolp function))
               (get function 'permanent-local-in-hooks))
      (put hook 'permanent-local-hook t)