bug#50506: 28.0.50; display-line-numbers equivalent for linum-format?

[Michael Gallagher - NOAA Affiliate via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>]

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OK. Here we go. I found some time last night. Attached is a git patch file
for changes that implement this feature request as well as (GNU) diffs for
the individual files in question. It's a pretty simple commit. It's worth
noting that I'm probably overlooking something in how I create the glyph, I
definitely don't understand the nuances of the display code. But I hope
it's helpful.

On Mon, Sep 13, 2021 at 12:27 PM Eli Zaretskii <eliz@gnu.org> wrote:

> > From: Michael Gallagher - NOAA Affiliate <michael.r.gallagher@noaa.gov>
> > Date: Mon, 13 Sep 2021 12:17:09 -0600
> > Cc: Lars Ingebrigtsen <larsi@gnus.org>, 50506@debbugs.gnu.org
> >
> > Funny enough, that's *exactly* what I tried to do, but I ran into
> problems getting the variable to display in
> > customize-variable (a problem with what I put in cus-start.el?) and if I
> manually used setq it didn't seem to
> > get translated correctly by the way I coded the macro.
>
> I think if you look up all the pieces that handle
> display-fill-column-indicator-character, both in C and in Lisp, you
> will have your answers.  Feel free to ask specific questions if
> something is still unclear after that.
>


-- 
Michael Gallagher, PhD
CIRES Research Scientist
Polar Observations and Processes Team (ESRL/NOAA/PSD)
325 Broadway, Boulder, Colorado 80305

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From f4c5fd9a8d49f6c1be66c2fddd3f506dcc92d547 Mon Sep 17 00:00:00 2001
From: polair <michael.r.gallagher@noaa.gov>
Date: Tue, 14 Sep 2021 10:12:14 -0600
Subject: [PATCH 21/21] add new variable for optional character to end of
 line-numbers line

---
 lisp/cus-start.el |  6 ++++++
 lisp/frame.el     |  1 +
 src/xdisp.c       | 16 ++++++++++++++++
 3 files changed, 23 insertions(+)

diff --git a/lisp/cus-start.el b/lisp/cus-start.el
index 1a3e5682bba..c755aaa41cf 100644
--- a/lisp/cus-start.el
+++ b/lisp/cus-start.el
@@ -740,6 +740,12 @@ minibuffer-prompt-properties--setter
                (const :tag "Visually relative line numbers"
                       :value visual))
               "26.1")
+             (display-line-numbers-separator-character
+              display-line-numbers
+              (character :tag "Character to separate numbers from buffer")
+              :safe (lambda (value) (or (characterp value) (null value)))
+              "28.05")
+              ;:safe (lambda (value) (or (characterp value) (null value))))
              (display-line-numbers-width
               display-line-numbers
               (choice
diff --git a/lisp/frame.el b/lisp/frame.el
index 60234fc2ae9..c6975a71cf2 100644
--- a/lisp/frame.el
+++ b/lisp/frame.el
@@ -2876,6 +2876,7 @@ set-frame-property--interactive
         header-line-format
         tab-line-format
         display-line-numbers
+        display-line-numbers-separator-character
         display-line-numbers-width
         display-line-numbers-current-absolute
         display-line-numbers-widen
diff --git a/src/xdisp.c b/src/xdisp.c
index d30a68570f0..92225af685a 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -23296,6 +23296,15 @@ maybe_produce_line_number (struct it *it)
 	}
     }
 
+  /* if last character in string, and separator is set, draw separator glyph */
+  if (FIXNATP (Vdisplay_line_numbers_separator_character))
+    {
+      tem_it.c = tem_it.char_to_display = XFIXNAT (Vdisplay_line_numbers_separator_character);
+      tem_it.len = 1;
+      SET_TEXT_POS (tem_it.position, -1, -1);
+      PRODUCE_GLYPHS (&tem_it);
+    }
+
   inhibit_free_realized_faces = save_free_realized_faces;
 
   /* Record the width in pixels we need for the line number display.  */
@@ -35509,6 +35518,13 @@ syms_of_xdisp (void)
   DEFSYM (Qrelative, "relative");
   DEFSYM (Qvisual, "visual");
 
+  DEFVAR_LISP ("display-line-numbers-separator-character", Vdisplay_line_numbers_separator_character,
+    doc: /* Character to draw between line numbers and buffer when non-nil. Some interesting
+options are: ├, ╞, │, ┃, ║, ▶, ⧽, and ⟫ */);
+  Vdisplay_line_numbers_separator_character = Qnil;
+  DEFSYM (Qdisplay_line_numbers_separator_character, "display-line-numbers-separator-character");
+  //Fmake_variable_buffer_local (Qdisplay_line_numbers_separator_character);
+
   DEFVAR_LISP ("display-line-numbers-width", Vdisplay_line_numbers_width,
     doc: /* Minimum width of space reserved for line number display.
 A positive number means reserve that many columns for line numbers,
-- 
2.33.0