saved user abbrevs and system abbrevs

[Glenn Morris]

Emacs 22 will introduce the concept of "user" and "system" abbrevs.
Only user abbrevs get saved into the abbrev-file. Reading the abbrev
file (happens at startup now) defines any saved abbrev-tables, and
populates them with the saved user abbrevs.

Most (all?) modes that define (system) abbrevs do it this way:

(defvar foo-abbrev-table
  (define-abbrev-table 'foo-abbrev-table nil)
  (define-abbrev foo-abbrev-table "foo" "foobar" nil 0 t)
  ...)

If foo-abbrev-table is already defined when the mode is loaded, the
system abbrevs don't get added.

The net result of this is that if a user saves an abbrev, when they
restart Emacs and load the appropriate mode, the system abbrevs do not
get defined.


Does anyone see a better fix than changing each mode that defines
abbrevs to use something like this:

(defvar foo-abbrev-table nil)

;; Do not override any user abbrev for "foo".
(unless (abbrev-expansion "foo" foo-abbrev-table)
  (define-abbrev foo-abbrev-table "foo" "foobar" nil 0 t))