Re: unload-feature questions and thoughts

[Juanma Barranquero]

On 10/17/07, Richard Stallman <address@hidden> wrote:

> I guess your idea is a good one.  Would you like to implement it?

The implementation is trivial (see the attached patch), other than
updating the docstring of `unload-feature', which I'm unable to do.

             Juanma


2007-10-17  Juanma Barranquero  <address@hidden>

        * loadhist.el (unload-function-features-list):
        Rename from `unload-hook-features-list'.
        (unload-hook-features-list): Add as obsolete alias.
        (unload-feature): Use `unload-function-features-list'
        and new FEATURE-unload-function.

Index: lisp/loadhist.el
===================================================================
RCS file: /sources/emacs/emacs/lisp/loadhist.el,v
retrieving revision 1.50
diff -c -b -r1.50 loadhist.el
*** lisp/loadhist.el    17 Oct 2007 23:03:55 -0000      1.50
--- lisp/loadhist.el    17 Oct 2007 23:16:28 -0000
***************
*** 137,147 ****
  `-hook' or `-hooks', from which `unload-feature' tries to remove
  pertinent symbols.")

! (defvar unload-hook-features-list nil
    "List of features of the package being unloaded.

! This is meant to be used by FEATURE-unload-hook hooks, see the
  documentation of `unload-feature' for details.")

  ;;;###autoload
  (defun unload-feature (feature &optional force)
--- 137,149 ----
  `-hook' or `-hooks', from which `unload-feature' tries to remove
  pertinent symbols.")

! (defvar unload-function-features-list nil
    "List of features of the package being unloaded.

! This is meant to be used by FEATURE-unload-function, see the
  documentation of `unload-feature' for details.")
+ (define-obsolete-variable-alias 'unload-hook-features-list
+     'unload-function-features-list "23.1")

  ;;;###autoload
  (defun unload-feature (feature &optional force)
***************
*** 172,190 ****
        (when dependents
        (error "Loaded libraries %s depend on %s"
               (prin1-to-string dependents) file))))
!   (let* ((unload-hook-features-list (feature-symbols feature))
!          (file (pop unload-hook-features-list))
         ;; If non-nil, this is a symbol for which we should
         ;; restore a previous autoload if possible.
         restore-autoload
!          (unload-hook (intern-soft (concat (symbol-name feature)
!                                            "-unload-hook"))))
      ;; Try to avoid losing badly when hooks installed in critical
      ;; places go away.  (Some packages install things on
      ;; `kill-buffer-hook', `activate-menubar-hook' and the like.)
      ;; First off, provide a clean way for package FOO to arrange
      ;; this by adding hooks on the variable `FOO-unload-hook'.
!     (if unload-hook
          (run-hooks unload-hook)
        ;; Otherwise, do our best.  Look through the obarray for symbols
        ;; which seem to be hook variables or special hook functions and
--- 174,198 ----
        (when dependents
        (error "Loaded libraries %s depend on %s"
               (prin1-to-string dependents) file))))
!   (let* ((unload-function-features-list (feature-symbols feature))
!          (file (pop unload-function-features-list))
         ;; If non-nil, this is a symbol for which we should
         ;; restore a previous autoload if possible.
         restore-autoload
!        (name (symbol-name feature))
!          (unload-hook (intern-soft (concat name "-unload-hook")))
!        (unload-func (intern-soft (concat name "-unload-function"))))
!     ;; If FEATURE-unload-function is defined and returns non-nil,
!     ;; don't try to do anything more; otherwise proceed normally.
!     (unless (and (bound-and-true-p unload-func)
!                (funcall unload-func))
        ;; Try to avoid losing badly when hooks installed in critical
        ;; places go away.  (Some packages install things on
        ;; `kill-buffer-hook', `activate-menubar-hook' and the like.)
+       (if unload-hook
          ;; First off, provide a clean way for package FOO to arrange
          ;; this by adding hooks on the variable `FOO-unload-hook'.
!         ;; This is obsolete; FEATURE-unload-function should be used now.
          (run-hooks unload-hook)
        ;; Otherwise, do our best.  Look through the obarray for symbols
        ;; which seem to be hook variables or special hook functions and
***************
*** 199,220 ****
                    (or (and (consp (symbol-value x)) ; Random hooks.
                             (string-match "-hooks?\\'" (symbol-name x)))
                        (memq x unload-feature-special-hooks))) ; Known 
abnormal hooks etc.
!          (dolist (y unload-hook-features-list)
             (when (and (eq (car-safe y) 'defun)
                        (not (get (cdr y) 'autoload)))
               (remove-hook x (cdr y)))))))
        ;; Remove any feature-symbols from auto-mode-alist as well.
!       (dolist (y unload-hook-features-list)
        (when (and (eq (car-safe y) 'defun)
                   (not (get (cdr y) 'autoload)))
          (setq auto-mode-alist
                (rassq-delete-all (cdr y) auto-mode-alist)))))
      (when (fboundp 'elp-restore-function) ; remove ELP stuff first
!       (dolist (elt unload-hook-features-list)
        (when (symbolp elt)
          (elp-restore-function elt))))

!     (dolist (x unload-hook-features-list)
        (if (consp x)
          (case (car x)
           ;; Remove any feature names that this file provided.
--- 207,228 ----
                      (or (and (consp (symbol-value x)) ; Random hooks.
                               (string-match "-hooks?\\'" (symbol-name x)))
                          (memq x unload-feature-special-hooks)))       ; Known 
abnormal hooks etc.
!            (dolist (y unload-function-features-list)
               (when (and (eq (car-safe y) 'defun)
                          (not (get (cdr y) 'autoload)))
                 (remove-hook x (cdr y)))))))
        ;; Remove any feature-symbols from auto-mode-alist as well.
!       (dolist (y unload-function-features-list)
          (when (and (eq (car-safe y) 'defun)
                     (not (get (cdr y) 'autoload)))
            (setq auto-mode-alist
                  (rassq-delete-all (cdr y) auto-mode-alist)))))
        (when (fboundp 'elp-restore-function) ; remove ELP stuff first
!       (dolist (elt unload-function-features-list)
          (when (symbolp elt)
            (elp-restore-function elt))))

!       (dolist (x unload-function-features-list)
        (if (consp x)
            (case (car x)
              ;; Remove any feature names that this file provided.
***************
*** 247,253 ****
        (unless (local-variable-if-set-p x)
          (makunbound x))))
      ;; Delete the load-history element for this file.
!     (setq load-history (delq (assoc file load-history) load-history)))
    ;; Don't return load-history, it is not useful.
    nil)

--- 255,261 ----
          (unless (local-variable-if-set-p x)
            (makunbound x))))
        ;; Delete the load-history element for this file.
!       (setq load-history (delq (assoc file load-history) load-history))))
    ;; Don't return load-history, it is not useful.
    nil)