Re: Changing of line format and undo

[Kim F. Storm]

In case you forgot:

RMS agreed to install the following change in emacs 22.



Stefan Monnier <address@hidden> writes:

>> Thanks, you are right ;-) Now I see what Eli meant. I still believe that
>> everything that can result in changing an external file should go into the
>> undo history but this is really a corner case of course.
>
> You can change C-x RET f to do what you want by having it add (manually in
> elisp) an `apply' entry to buufer-undo-list.
>
> E.g. I've changed my set-buffer-multibyte to do that (waiting for post-22
> to commit it).
>
>
>         Stefan
>
>
> --- orig/src/buffer.c
> +++ mod/src/buffer.c
> @@ -2112,10 +2100,11 @@
>  {
>    struct Lisp_Marker *tail, *markers;
>    struct buffer *other;
> -  int undo_enabled_p = !EQ (current_buffer->undo_list, Qt);
>    int begv, zv;
>    int narrowed = (BEG != BEGV || Z != ZV);
>    int modified_p = !NILP (Fbuffer_modified_p (Qnil));
> +  Lisp_Object old_undo = current_buffer->undo_list;
> +  struct gcpro gcpro1;
>  
>    if (current_buffer->base_buffer)
>      error ("Cannot do `set-buffer-multibyte' on an indirect buffer");
> @@ -2124,10 +2113,11 @@
>    if (NILP (flag) == NILP (current_buffer->enable_multibyte_characters))
>      return flag;
>  
> -  /* It would be better to update the list,
> -     but this is good enough for now.  */
> -  if (undo_enabled_p)
> -    current_buffer->undo_list = Qt;
> +  GCPRO1 (old_undo);
> +
> +  /* Don't record these buffer changes.  We will put a special undo entry
> +     instead.  */
> +  current_buffer->undo_list = Qt;
>  
>    /* If the cached position is for this buffer, clear it out.  */
>    clear_charpos_cache (current_buffer);
> @@ -2327,8 +2317,18 @@
>        set_intervals_multibyte (1);
>      }
>  
> -  if (undo_enabled_p)
> -    current_buffer->undo_list = Qnil;
> +  if (!EQ (old_undo, Qt))
> +    {
> +      /* Represent all the above changes by a special undo entry.  */
> +      extern Lisp_Object Qapply;
> +      Lisp_Object args[3];
> +      args[0] = Qapply;
> +      args[1] = Qset_buffer_multibyte;
> +      args[2] = NILP (flag) ? Qt : Qnil;
> +      current_buffer->undo_list = Fcons (Flist (3, args), old_undo);
> +    }
> +
> +  UNGCPRO;
>  
>    /* Changing the multibyteness of a buffer means that all windows
>       showing that buffer must be updated thoroughly.  */

-- 
Kim F. Storm <address@hidden> http://www.cua.dk