bug#5937: 23.1.95; why saving empty abbrev tables

[Leo <sdl.web@gmail.com>]

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On 2010-04-27 11:49 +0800, Stefan Monnier wrote:
> Actually, having tried it now for a while I do have an objection: it
> makes it harder to add entries to an abbrev-table if that table
> is empty.
>
> So I think a better option is to sort the tables such that empty tables
> are pushed to the end.
>
>
>         Stefan

Hello Stefan,

I propose we allow C-u M-x edit-abbrevs to include all abbrev tables but
default to include only nonempty tables.

Here is an updated patch.


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=== modified file 'lisp/abbrev.el'
--- lisp/abbrev.el	2011-03-22 15:38:40 +0000
+++ lisp/abbrev.el	2011-03-27 04:56:22 +0000
@@ -104,7 +104,7 @@
 prefix arg, display only local, i.e. mode-specific, abbrevs.
 Otherwise display all abbrevs."
   (interactive "P")
-  (display-buffer (prepare-abbrev-list-buffer local)))
+  (display-buffer (prepare-abbrev-list-buffer (and local 'local))))
 
 (defun abbrev-table-name (table)
   "Value is the name of abbrev table TABLE."
@@ -116,14 +116,28 @@
       (setq tables (cdr tables)))
     found))
 
-(defun prepare-abbrev-list-buffer (&optional local)
-  (let ((local-table local-abbrev-table))
+(defun abbrev-nonempty-table-names (&optional ignore-system)
+  "Return a list of nonempty abbrev table names.
+If IGNORE-SYSTEM is non-nil, system definitions are ignored."
+  (delete nil
+          (mapcar (lambda (tn)
+                    (unless (abbrev-table-empty-p
+                             (symbol-value tn) ignore-system)
+                      tn))
+                  abbrev-table-name-list)))
+
+;; HOW takes value: nil, local or all.
+(defun prepare-abbrev-list-buffer (&optional how)
+  (let ((local-table local-abbrev-table)
+        (tables (if (eq how 'all)
+                    abbrev-table-name-list
+                  (abbrev-nonempty-table-names))))
     (with-current-buffer (get-buffer-create "*Abbrevs*")
       (erase-buffer)
-      (if local
+      (if (eq how 'local)
           (insert-abbrev-table-description
            (abbrev-table-name local-table) t)
-        (dolist (table abbrev-table-name-list)
+        (dolist (table tables)
           (insert-abbrev-table-description table t)))
       (goto-char (point-min))
       (set-buffer-modified-p nil)
@@ -140,10 +154,11 @@
   (use-local-map edit-abbrevs-map)
   (run-mode-hooks 'edit-abbrevs-mode-hook))
 
-(defun edit-abbrevs ()
+(defun edit-abbrevs (&optional all)
   "Alter abbrev definitions by editing a list of them.
 Selects a buffer containing a list of abbrev definitions.
-You can edit them and type \\<edit-abbrevs-map>\\[edit-abbrevs-redefine] to redefine abbrevs
+Use \\[universal-argument] to include empty abbrev tables.  You can edit
+them and type \\<edit-abbrevs-map>\\[edit-abbrevs-redefine] to redefine abbrevs
 according to your editing.
 Buffer contains a header line for each abbrev table,
  which is the abbrev table name in parentheses.
@@ -152,8 +167,8 @@
 where NAME and EXPANSION are strings with quotes,
 USECOUNT is an integer, and HOOK is any valid function
 or may be omitted (it is usually omitted)."
-  (interactive)
-  (switch-to-buffer (prepare-abbrev-list-buffer)))
+  (interactive "P")
+  (switch-to-buffer (prepare-abbrev-list-buffer (and all 'all))))
 
 (defun edit-abbrevs-redefine ()
   "Redefine abbrevs according to current buffer contents."
@@ -225,7 +240,8 @@
 		    abbrev-file-name)))
   (or (and file (> (length file) 0))
       (setq file abbrev-file-name))
-  (let ((coding-system-for-write 'utf-8))
+  (let ((coding-system-for-write 'utf-8)
+        (tables (abbrev-nonempty-table-names t)))
     (with-temp-buffer
       (dolist (table
 	       ;; We sort the table in order to ease the automatic
@@ -234,10 +250,9 @@
 	       ;; user keeps their home directory in a revision
 	       ;; control system, and is therefore keeping multiple
 	       ;; slightly-differing copies loosely synchronized.
-	       (sort (copy-sequence abbrev-table-name-list)
-		     (lambda (s1 s2)
-		       (string< (symbol-name s1)
-				(symbol-name s2)))))
+	       (sort tables (lambda (s1 s2)
+			      (string< (symbol-name s1)
+				       (symbol-name s2)))))
 	(insert-abbrev-table-description table nil))
       (when (unencodable-char-position (point-min) (point-max) 'utf-8)
 	(setq coding-system-for-write
@@ -420,6 +435,18 @@
   (and (vectorp object)
        (numberp (abbrev-table-get object :abbrev-table-modiff))))
 
+(defun abbrev-table-empty-p (object &optional ignore-system)
+  "Return nil if there are no abbrev symbols in OBJECT.
+If IGNORE-SYSTEM is non-nil, system definitions are ignored."
+  (unless (abbrev-table-p object)
+    (error "Non abbrev table object"))
+  (not (catch 'some
+         (mapatoms (lambda (abbrev)
+                     (unless (or (zerop (length (symbol-name abbrev)))
+                                 (and ignore-system (abbrev-get abbrev :system)))
+                       (throw 'some t)))
+                   object))))
+
 (defvar global-abbrev-table (make-abbrev-table)
   "The abbrev table whose abbrevs affect all buffers.
 Each buffer may also have a local abbrev table.


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Leo