Subject: bug#23794: Emacs bug #23794; sort-line behavior regressed from prior Emacs versions

From: Robert Weiner <[email-masked]>
Date: Sun, 19 Jun 2016 12:51:08 -0400

On Sun, Jun 19, 2016 at 12:30 PM, Eli Zaretskii <[email-masked]> wrote:

> Didn't think that far, but is it really clean for sort-lines to have
> special code for some major mode?  I thought a better way is to
> override the default behavior by having sort-lines call functions
> through funcall or somesuch, and then outline modes could set the
> appropriate variable to the function of their liking?
>

The problem with that approach is that each mode has to be aware of this
and add a setting, really not much different than each mode having its own
sort function or way of calling a sort function.  It is much more useful to
centralize the behavior within the sorting library, even if it adds some
conditional complexity to the code.  Here is the suggested patch to do it
this way.  -- Bob

*** sort-orig.el.gz 2016-06-19 12:42:12.000000000 -0400
--- sort.el.gz 2016-06-19 12:42:12.000000000 -0400
***************
*** 39,44 ****
--- 39,50 ----
    :type 'boolean)
  ;;;###autoload(put 'sort-fold-case 'safe-local-variable 'booleanp)

+ (defcustom sort-invisible-lines nil
+   "Non-nil if the buffer `sort-line' function should treat invisible
lines like visible ones."
+   :group 'sort
+   :type 'boolean)
+ ;;;###autoload(put 'sort-invisible-lines 'safe-local-variable 'booleanp)
+
  ;;;###autoload
  (defun sort-subr (reverse nextrecfun endrecfun
   &optional startkeyfun endkeyfun predicate)
***************
*** 210,216 ****
        (goto-char (point-min))
        (let ;; To make `end-of-line' and etc. to ignore fields.
   ((inhibit-field-text-motion t))
! (sort-subr reverse 'forward-line 'end-of-line)))))

  ;;;###autoload
  (defun sort-paragraphs (reverse beg end)
--- 216,228 ----
        (goto-char (point-min))
        (let ;; To make `end-of-line' and etc. to ignore fields.
   ((inhibit-field-text-motion t))
! (if (and (not sort-invisible-lines)
! (or (derived-mode-p 'outline-mode)
!     (and (boundp 'outline-minor-mode) outline-minor-mode)))
!    ;; In in an outline mode with sort-invisible-lines nil, sort
!    ;; only visible lines.
!    (sort-subr reverse 'forward-visible-line 'end-of-visible-line)
!  (sort-subr reverse 'forward-line 'end-of-line))))))

  ;;;###autoload
  (defun sort-paragraphs (reverse beg end)

*** simple-orig.el.gz 2016-06-18 11:29:58.000000000 -0400
--- simple.el.gz 2016-06-18 11:29:58.000000000 -0400
***************
*** 4909,4918 ****
  (kill-region (point)
       (progn (forward-visible-line arg) (point))))))

! (defun forward-visible-line (arg)
!   "Move forward by ARG lines, ignoring currently invisible newlines only.
  If ARG is negative, move backward -ARG lines.
  If ARG is zero, move to the beginning of the current line."
    (condition-case nil
        (if (> arg 0)
   (progn
--- 4909,4919 ----
  (kill-region (point)
       (progn (forward-visible-line arg) (point))))))

! (defun forward-visible-line (&optional arg)
!   "Move forward by optional ARG lines (default = 1), ignoring currently
invisible newlines only.
  If ARG is negative, move backward -ARG lines.
  If ARG is zero, move to the beginning of the current line."
+   (if (null arg) (setq arg 1))
    (condition-case nil
        (if (> arg 0)
   (progn