Re: saved user abbrevs and system abbrevs

[Glenn Morris]

Richard Stallman wrote:

>     (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))
>
> Maybe we should change define-abbrev so that defining a system
> abbrev does not override any user abbrev (unless you specify
> "override") in some way.

OK. I was really wondering if there was some way to avoid the problem
of not being able to initialize an abbrev-table in its defvar, since
it seems a bit odd/annoying/hard to remember. But I guess that there
isn't really, and that it does not matter that much.

Here's a patch for your suggestion.

*** abbrev.c   18 Apr 2006 20:57:56 -0000 1.69
--- abbrev.c   1 Dec 2006 02:47:52 -0000
***************
*** 83,89 ****
  
  Lisp_Object Vpre_abbrev_expand_hook, Qpre_abbrev_expand_hook;
  
! Lisp_Object Qsystem_type, Qcount;
  
  DEFUN ("make-abbrev-table", Fmake_abbrev_table, Smake_abbrev_table,
  0, 0, 0,
         doc: /* Create a new, empty abbrev table object.  */)
--- 83,89 ----
  
  Lisp_Object Vpre_abbrev_expand_hook, Qpre_abbrev_expand_hook;
  
! Lisp_Object Qsystem_type, Qcount, Qforce;
  
  DEFUN ("make-abbrev-table", Fmake_abbrev_table, Smake_abbrev_table,
  0, 0, 0,
         doc: /* Create a new, empty abbrev table object.  */)
***************
*** 123,129 ****
  \(The default is zero.)
  
  SYSTEM-FLAG, if non-nil, says that this is a "system" abbreviation
! which should not be saved in the user's abbreviation file.  */)
       (table, name, expansion, hook, count, system_flag)
       Lisp_Object table, name, expansion, hook, count, system_flag;
  {
--- 123,131 ----
  \(The default is zero.)
  
  SYSTEM-FLAG, if non-nil, says that this is a "system" abbreviation
! which should not be saved in the user's abbreviation file.
! Unless SYSTEM-FLAG is `force', a system abbreviation will not
! overwrite a non-system abbreviation of the same name.  */)
       (table, name, expansion, hook, count, system_flag)
       Lisp_Object table, name, expansion, hook, count, system_flag;
  {
***************
*** 131,136 ****
--- 133,148 ----
    CHECK_VECTOR (table);
    CHECK_STRING (name);
  
+   /* If defining a system abbrev, do not overwrite a non-system abbrev
+      of the same name, unless 'force is used. */
+   if (!NILP (system_flag) && !EQ (system_flag, Qforce))
+     {
+       sym = Fintern_soft (name, table);
+ 
+       if (!NILP (SYMBOL_VALUE (sym)) &&
+           NILP (Fplist_get (XSYMBOL (sym)->plist, Qsystem_type))) return Qnil;
+     }
+ 
    if (NILP (count))
      count = make_number (0);
    else
***************
*** 640,645 ****
--- 652,660 ----
    Qcount = intern ("count");
    staticpro (&Qcount);
  
+   Qforce = intern ("force");
+   staticpro (&Qforce);
+ 
    DEFVAR_LISP ("abbrev-table-name-list", &Vabbrev_table_name_list,
           doc: /* List of symbols whose values are abbrev tables.
           */);
    Vabbrev_table_name_list = Fcons (intern
           ("fundamental-mode-abbrev-table"),