bug#5937: 23.1.95; why saving empty abbrev tables

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

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On 2010-04-12 19:32 +0100, Stefan Monnier wrote:
>> It seems to make it more difficult for editing (edit-abbrevs) because
>> the buffer is full of empty abbrev.  I wonder if saving only non-empty
>> tables is better and user friendlier.
>
> It does sound like a good idea.  Any objection?

Would the following patch be acceptable?

* lisp/abbrev.el (write-abbrev-file prepare-abbrev-list-buffer):
ignore empty abbrev tables
  (abbrev-table-empty-p): new function.


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diff --git a/lisp/abbrev.el b/lisp/abbrev.el
index b72bdbb..21411a5 100644
--- a/lisp/abbrev.el
+++ b/lisp/abbrev.el
@@ -127,15 +127,20 @@ Otherwise display all abbrevs."
 (defun prepare-abbrev-list-buffer (&optional local)
   (with-current-buffer (get-buffer-create "*Abbrevs*")
     (erase-buffer)
-    (if local
-        (insert-abbrev-table-description
-         (abbrev-table-name local-abbrev-table) t)
-      (dolist (table abbrev-table-name-list)
-        (insert-abbrev-table-description table t)))
-    (goto-char (point-min))
-    (set-buffer-modified-p nil)
-    (edit-abbrevs-mode)
-    (current-buffer)))
+    (let ((abbrev-table-name-list
+           (delete nil (mapcar (lambda (tn)
+                                 (unless (abbrev-table-empty-p (symbol-value tn))
+                                   tn))
+                               abbrev-table-name-list))))
+      (if local
+          (insert-abbrev-table-description
+           (abbrev-table-name local-abbrev-table) t)
+        (dolist (table abbrev-table-name-list)
+          (insert-abbrev-table-description table t)))
+      (goto-char (point-min))
+      (set-buffer-modified-p nil)
+      (edit-abbrevs-mode)
+      (current-buffer))))
 
 (defun edit-abbrevs-mode ()
   "Major mode for editing the list of abbrev definitions.
@@ -232,7 +237,12 @@ specified in `abbrev-file-name' is used."
 		    abbrev-file-name)))
   (or (and file (> (length file) 0))
       (setq file abbrev-file-name))
-  (let ((coding-system-for-write 'emacs-mule))
+  (let ((coding-system-for-write 'emacs-mule)
+        (tables (delete nil (mapcar
+                             (lambda (tn)
+                               (unless (abbrev-table-empty-p (symbol-value tn))
+                                 tn))
+                             abbrev-table-name-list))))
     (with-temp-file file
       (insert ";;-*-coding: emacs-mule;-*-\n")
       (dolist (table
@@ -242,10 +252,9 @@ specified in `abbrev-file-name' is used."
                ;; 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)))))
 \f
 (defun add-mode-abbrev (arg)
@@ -419,6 +428,16 @@ PROPS is a list of properties."
   (and (vectorp object)
        (numberp (abbrev-table-get object :abbrev-table-modiff))))
 
+(defun abbrev-table-empty-p (object)
+  "Return nil if there are no abbrev symbols in OBJECT."
+  (unless (abbrev-table-p object)
+    (error "Non abbrev table object"))
+  (not (catch 'some
+         (mapatoms (lambda (sym)
+                     (when (symbol-value sym)
+                       (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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Thanks,
Leo