Re: Customize and autoloaded libraries

[Stefan Monnier]

> (defun custom-initialize-hook (symbol value)
>   "Initialize SYMBOL with VALUE.
> 
> If symbol has a `saved-value' property, it will evaluate the car of
> that.  The result should be a list of hook functions, which will be
> added to SYMBOL using `add-hook'.  If there is no `saved-value'
> property, VALUE will be evaluated instead to get the list of hook
> functions to add to the symbol.
> 
> This is for initialization hook variables.  It is different from the
> other initialize functions in that the saved or initial value is
> merged into the existing value, allowing the user to use `add-hook'
> before the declaration of the hook variable."
>   (let ((hooks (if (get symbol 'saved-value)
>                  (eval (car (get symbol 'saved-value)))
>                (eval value))))
>     (mapc (lambda (fun) (add-hook symbol fun)) hooks)))

One thing bothers me here: it makes the defhook behave more
like defconst than defvar.  More specifically, if you do

        (defhook foo-hook '(bar))
        (remove-hook 'foo-hook 'bar)
        (defhook foo-hook '(bar))

foo-hook will contain bar even though you clearly wanted to remove it.
So I think we need to remember that initialization took place.
Something like:

 (defun custom-initialize-hook (symbol value)
   (if (get symbol 'custom-initialized) nil
     (dolist (fun (reverse (eval (if (get symbol 'saved-value)
                                     (car (get symbol 'saved-value))
                                   value))))
       ;; Use `append' to pretend that `fun' was there long ago.
       (add-hook symbol fun t))
     (put symbol 'custom-initialized t)))


-- Stefan