Subject: bug#59438: 29.0.50; [PATCH] Make defvar's into defcustom's in tab-line

From: Gabriel <[email-masked]>
Date: Mon, 21 Nov 2022 06:25:17 -0300

Description:

Please find attached a patch that proposes the following minor changes
to tab-line.  I can refactor the patch if we decide that some change are
not worth or if it's better to split it into smaller patches.

1) Turn the following defvar's into defcustom's:

- `tab-line-tabs-buffer-group-function'
- `tab-line-tabs-buffer-group-sort-function'
- `tab-line-tabs-buffer-groups-sort-function'

2) Add conditional around function call of
`tab-line-tabs-buffer-groups-sort-function', in
`tab-line-tabs-buffer-groups'.  This guards against nil values, similar
to how `tab-line-tabs-buffer-group-sort-function is handled, making the
behavior more consistent across these two (similar) variables.

Should we announce these "new" defcustom's in NEWS?

>From da1053e7211d8bb17769fe43650a9bcdd359aeab Mon Sep 17 00:00:00 2001
From: Gabriel do Nascimento Ribeiro <[email-masked]>
Date: Mon, 21 Nov 2022 06:17:49 -0300
Subject: [PATCH 1/1] Make defvar's into defcustom's in tab-line

* lisp/tab-line.el (tab-line-tabs-buffer-group-function)
  (tab-line-tabs-buffer-group-sort-function)
  (tab-line-tabs-buffer-groups-sort-function): Make into defcustom's.
  (Make defvar's into defcustom's in tab-line): Handle case when
  variable tab-line-tabs-buffer-groups-sort-function is nil.
---
 lisp/tab-line.el | 51 ++++++++++++++++++++++++++++--------------------
 1 file changed, 30 insertions(+), 21 deletions(-)

diff --git a/lisp/tab-line.el b/lisp/tab-line.el
index 99a785ee3e..9b1c101718 100644
--- a/lisp/tab-line.el
+++ b/lisp/tab-line.el
@@ -341,16 +341,26 @@ tab-line-tabs-mode-buffers
                                            (derived-mode-p mode)))
                              (funcall tab-line-tabs-buffer-list-function)))))
 
-(defvar tab-line-tabs-buffer-group-function nil
+(defcustom tab-line-tabs-buffer-group-function nil
   "Function to add a buffer to the appropriate group of tabs.
-Takes a buffer as arg and should return a group name as a string.
-If the return value is nil, the buffer should be filtered out.")
+Takes a buffer as argument and should return a group name as a
+string.  If the return value is nil, the buffer should be
+ filtered out."
+  :type 'function
+  :group 'tab-line
+  :version "29.1")
 
-(defvar tab-line-tabs-buffer-group-sort-function nil
-  "Function to sort buffers in a group.")
+(defcustom tab-line-tabs-buffer-group-sort-function nil
+  "Function to sort buffers in a group."
+  :type 'function
+  :group 'tab-line
+  :version "29.1")
 
-(defvar tab-line-tabs-buffer-groups-sort-function #'string<
-  "Function to sort group names.")
+(defcustom tab-line-tabs-buffer-groups-sort-function #'string<
+  "Function to sort group names."
+  :type 'function
+  :group 'tab-line
+  :version "29.1")
 
 (defvar tab-line-tabs-buffer-groups mouse-buffer-menu-mode-groups
   "How to group various major modes together in the tab line.
@@ -378,13 +388,14 @@ tab-line-tabs-buffer-groups
 generate the group name."
   (if (window-parameter nil 'tab-line-groups)
       (let* ((buffers (funcall tab-line-tabs-buffer-list-function))
-             (groups
-              (seq-sort tab-line-tabs-buffer-groups-sort-function
-                        (delq nil (mapcar #'car (seq-group-by
-                                                 (lambda (buffer)
-                                                   (tab-line-tabs-buffer-group-name
-                                                    buffer))
-                                                 buffers)))))
+             (groups (delq nil
+                           (mapcar #'car
+                                   (seq-group-by #'tab-line-tabs-buffer-group-name
+                                                 buffers))))
+             (sorted-groups (if (functionp tab-line-tabs-buffer-groups-sort-function)
+                                (seq-sort tab-line-tabs-buffer-groups-sort-function
+                                          groups)
+                              groups))
              (selected-group (window-parameter nil 'tab-line-group))
              (tabs
               (mapcar (lambda (group)
@@ -395,9 +406,8 @@ tab-line-tabs-buffer-groups
                                        (set-window-parameter nil 'tab-line-groups nil)
                                        (set-window-parameter nil 'tab-line-group group)
                                        (set-window-parameter nil 'tab-line-hscroll nil)))))
-                      groups)))
-        tabs)
-
+                      sorted-groups)))
+             tabs)
     (let* ((window-parameter (window-parameter nil 'tab-line-group))
            (group-name (tab-line-tabs-buffer-group-name (current-buffer)))
            (group (prog1 (or window-parameter group-name "All")
@@ -410,10 +420,9 @@ tab-line-tabs-buffer-groups
                                      (set-window-parameter nil 'tab-line-groups t)
                                      (set-window-parameter nil 'tab-line-group group)
                                      (set-window-parameter nil 'tab-line-hscroll nil)))))
-           (buffers
-            (seq-filter (lambda (b)
-                          (equal (tab-line-tabs-buffer-group-name b) group))
-                        (funcall tab-line-tabs-buffer-list-function)))
+           (buffers (seq-filter (lambda (b)
+                                  (equal (tab-line-tabs-buffer-group-name b) group))
+                                (funcall tab-line-tabs-buffer-list-function)))
            (sorted-buffers (if (functionp tab-line-tabs-buffer-group-sort-function)
                                (seq-sort tab-line-tabs-buffer-group-sort-function
                                          buffers)
-- 
2.34.1

---
Gabriel