bug#37179: 27.0.50; tabulated-list-mode creates obsolete empty line on the end

[Jean Louis]

I have tried that, and I like previous behavior so much more, as in
tabulated mode, the cursor then escapes on the end of line, which is
really not intended so.

In my opinion it is better to leave it as it is, and that I improve
my personal program that stops reacting on the end of line.

Jean

* Stefan Kangas <stefan@marxist.se> [2020-10-19 02:56]:
> Jean Louis <bugs@gnu.support> writes:
> 
> > Here is sample demonstration:
> >
> > (define-derived-mode my-mode tabulated-list-mode "My Mode" "My mode"
> >   (setq tabulated-list-format [("ID" 5 t . (:right-align t))
> >                                ("Hyperlink" 30 t)
> >                                ("Type" 10 t)])
> >   (setq tabulated-list-padding 1)
> >   (setq tabulated-list-sort-key (cons "ID" nil))
> >   (tabulated-list-init-header))
> >
> > (defun my-set-list (&optional parent)
> >   (interactive)
> >   (let ((buffer "*Hyperspace*"))
> >     (pop-to-buffer buffer nil)
> >     (read-only-mode 0)
> >     (erase-buffer)
> >     (read-only-mode 1)
> >     (my-mode)
> >     (hl-line-mode)
> >     (setq tabulated-list-entries (list
> >                               (list "1" ["1" "Link 1" "Type"])
> >                               (list "2" ["2" "Link 2" "Type"])))
> >     (tabulated-list-print t)))
> >
> > When it is defined the M-x my-set-list allows me to go after the last
> > line. Yet that is not logical, and empty line shall not be displayed, as
> > it does not exist in the tabulated-list-entries variable.
> >
> > Video demonstration 1MB:
> > https://gnu.support/images/2019/08/2019-08-25/2019-08-25-11:15:46.ogv
> 
> I tend to agree; there doesn't seem to be any point to go to a line
> after the last entry.
> 
> But this issue is not unique to tabulated-list-mode, and in fact crops
> up in all kinds of places in Emacs.  IME, the usual solution is to just
> leave the final newline, and maybe there are good reasons for that.  See
> Dired for example, or Gnus.
> 
> As an experiment, I came up with the attached patch that removes the
> final newline in `tabulated-list-mode'.  As expected, it is not without
> issues: `end-of-buffer' leaves point at the end of last line.  If that
> line is very long, we can end up scrolled far to the right, which is
> rather unsettling.  Another thing that may or may not be problematic (I
> didn't test it) is if we have commands that operate on regions of lines.
> 
> So I'm not exactly sure what to do here.  Perhaps we should just leave
> it alone...  Or maybe there is some smart solution just waiting to be
> discovered.
> 
> Does anyone else have any comments?

> diff --git a/lisp/emacs-lisp/tabulated-list.el 
> b/lisp/emacs-lisp/tabulated-list.el
> index 2f7899ec51..7079eaad03 100644
> --- a/lisp/emacs-lisp/tabulated-list.el
> +++ b/lisp/emacs-lisp/tabulated-list.el
> @@ -480,6 +480,11 @@ tabulated-list-print
>                (forward-line 1)
>                (delete-region old (point))))))
>        (setq entries (cdr entries)))
> +    ;; Remove empty last line.
> +    (save-excursion
> +      (let ((inhibit-read-only t))
> +        (goto-char (point-max))
> +        (delete-char -1)))
>      (set-buffer-modified-p nil)
>      ;; If REMEMBER-POS was specified, move to the "old" location.
>      (if saved-pt