Re: org-mode and mode hooks.

[Luc Teirlinck]

Stefan Monnier wrote:

   W.r.t the code bundled with Emacs, there's often no problem (tho, sometimes
   there is, because it's not always trivial to fix the code to use
   define-derived-mode), but for the unbundled packages, the change:

   2005-05-22  Luc Teirlinck  <address@hidden>

           * emacs-lisp/easy-mmode.el (define-global-minor-mode): Use
           `after-change-major-mode-hook' instead of `find-file-hook'.

   introduced a bug where (typically) global-font-lock chooses the wrong
   keywords (the ones of the parent mode rather than ones of the actual major
   mode).

Well, it fixed one bug, but it created more occurrences of another existing
bug.  The bug it fixed relates to timers and processes calling mode
functions.  The other existing bug that it creates more occurrences of
is that if _anything_ enables font-lock before the final mode is into
place (for instance a function added by a user to a hook) font-lock
chooses the wrong keywords.  Granted, my change makes this much more
likely to happen (of course).  But even without my change it can happen.

The following changes fix both bugs, by using post-command-hook to
check whether font-lock was enabled for the correct mode and adapting
the turn-on function to be able to correct it.  I still will have to
see whether this automatically fixes the second bug for other
functions defined with define-global-mode, or whether some of them
need a slightly different turn-on function too.

===File ~/font-core-diff====================================
*** font-core.el        22 May 2005 16:46:07 -0500      1.28
--- font-core.el        25 May 2005 21:57:50 -0500      
***************
*** 284,291 ****
      (let (inhibit-quit)
        (turn-on-font-lock))))
  
  (easy-mmode-define-global-mode
!  global-font-lock-mode font-lock-mode turn-on-font-lock-if-enabled
   :extra-args (dummy))
  
  ;;; End of Global Font Lock mode.
--- 284,295 ----
      (let (inhibit-quit)
        (turn-on-font-lock))))
  
+ (defun turn-on-font-lock-as-appropriate ()
+   (let (font-lock-set-defaults)
+     (turn-on-font-lock-if-enabled)))
+ 
  (easy-mmode-define-global-mode
!  global-font-lock-mode font-lock-mode turn-on-font-lock-as-appropriate
   :extra-args (dummy))
  
  ;;; End of Global Font Lock mode.
============================================================

===File ~/easy-mmode-diff===================================
*** easy-mmode.el       22 May 2005 16:50:33 -0500      1.63
--- easy-mmode.el       25 May 2005 22:37:54 -0500      
***************
*** 263,268 ****
--- 263,271 ----
  ;;; make global minor mode
  ;;;
  
+ (defvar easy-mmode-stored-mode nil)
+ (make-variable-buffer-local 'easy-mmode-stored-mode)
+ 
  ;;;###autoload
  (defalias 'easy-mmode-define-global-mode 'define-global-minor-mode)
  ;;;###autoload
***************
*** 278,283 ****
--- 281,287 ----
         (group nil)
         (extra-args nil)
         (buffers (intern (concat global-mode-name "-buffers")))
+        (check-buffers (intern (concat "check-" global-mode-name "-buffers")))
         (cmmh (intern (concat global-mode-name "-cmmh"))))
  
      ;; Check keys.
***************
*** 307,314 ****
--- 311,320 ----
         (if ,global-mode
             (progn
               (add-hook 'after-change-major-mode-hook ',buffers)
+              (add-hook 'find-file-hook ',buffers)
               (add-hook 'change-major-mode-hook ',cmmh))
           (remove-hook 'after-change-major-mode-hook ',buffers)
+          (remove-hook 'find-file-hook ',buffers)
           (remove-hook 'change-major-mode-hook ',cmmh))
  
         ;; Go through existing buffers.
***************
*** 325,341 ****
  
         ;; The function that calls TURN-ON in each buffer.
         (defun ,buffers ()
!        (remove-hook 'post-command-hook ',buffers)
         (while ,buffers
           (let ((buf (pop ,buffers)))
             (when (buffer-live-p buf)
!              (with-current-buffer buf (,turn-on))))))
!        (put ',buffers 'definition-name ',global-mode)
  
         ;; The function that catches kill-all-local-variables.
         (defun ,cmmh ()
         (add-to-list ',buffers (current-buffer))
!        (add-hook 'post-command-hook ',buffers))
         (put ',cmmh 'definition-name ',global-mode))))
  
  ;;;
--- 331,360 ----
  
         ;; The function that calls TURN-ON in each buffer.
         (defun ,buffers ()
!        (dolist (buf ,buffers)
!          (when (buffer-live-p buf)
!            (with-current-buffer buf
!              (unless ,mode
!                (setq easy-mmode-stored-mode major-mode)
!                (,turn-on))))))
!        (put ',buffers 'definition-name ',global-mode)
! 
!        (defun ,check-buffers ()
!        (remove-hook 'post-command-hook ',check-buffers)
         (while ,buffers
           (let ((buf (pop ,buffers)))
             (when (buffer-live-p buf)
!              (with-current-buffer buf
!                (if ,mode
!                    (unless (eq easy-mmode-stored-mode major-mode)
!                      (,mode -1)
!                      (,turn-on))
!                  (,turn-on)))))))
  
         ;; The function that catches kill-all-local-variables.
         (defun ,cmmh ()
         (add-to-list ',buffers (current-buffer))
!        (add-hook 'post-command-hook ',check-buffers))
         (put ',cmmh 'definition-name ',global-mode))))
  
  ;;;
============================================================