bug#41473: Not saving all user options

[Philip K.]

Hi,

I was rewriting parts of my configuration recently, and one important
change was to use `customize-set-variable' more extensivly (via a
setq-like macro). What annoys me is that even though I specify all the
variables in my init.el, they eventually get regenerated in my
`custom-file'. The standard solutions seems to have been setting
`custom-file' to /dev/null, but since I like to use the ECI for
temporary changes.

What I would be interested in, would be a way to tell customize not to
write out a user-option, to keep configurations cleaner. I tried this in
the patch bellow, by checking of the comment starts with four or more
spaces, but it could just as well be any other predicate such as a
string starting with a zero-width whitespace, the string "NONSAVE" or a
property in the symbol plist. The important thing would be that macros
such as my setq-like macro, or use-package could keep the entire
configuration cleaner, without having to give up on a `custom-file'
entierly -- ideally a pure user wouldn't even notice.

Is there any argument against something like this in principle, or is
there already such a mechanism I overlooked?

-- 
        Philip K.

>From 06d4030245e037b2e7e88180cda542c5ebd22ebb Mon Sep 17 00:00:00 2001
From: Philip K <philip@warpmail.net>
Date: Sat, 23 May 2020 09:47:49 +0200
Subject: [PATCH] Inhibit saving user options when comments start with =<4
 spaces

---
 lisp/cus-edit.el | 20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/lisp/cus-edit.el b/lisp/cus-edit.el
index 1ec2708550..510b1b3711 100644
--- a/lisp/cus-edit.el
+++ b/lisp/cus-edit.el
@@ -4594,17 +4594,21 @@ custom-save-variables
   (save-excursion
     (custom-save-delete 'custom-set-variables)
     (let ((standard-output (current-buffer))
-         (saved-list (make-list 1 0))
-         sort-fold-case)
+         saved-list sort-fold-case)
       ;; First create a sorted list of saved variables.
       (mapatoms
        (lambda (symbol)
-        (if (and (get symbol 'saved-value)
-                 ;; ignore theme values
-                 (or (null (get symbol 'theme-value))
-                     (eq 'user (caar (get symbol 'theme-value)))))
-            (nconc saved-list (list symbol)))))
-      (setq saved-list (sort (cdr saved-list) 'string<))
+        (when (and (get symbol 'saved-value)
+                    ;; don't save comments with four or more preceding
+                    ;; space charachters
+                    (not (string-match-p
+                          "^[[:space:]]{4,}"
+                          (get symbol 'saved-variable-comment)))
+                   ;; ignore theme values
+                   (or (null (get symbol 'theme-value))
+                       (eq 'user (caar (get symbol 'theme-value)))))
+          (push symbol saved-list))))
+      (setq saved-list (sort saved-list 'string<))
       (unless (bolp)
        (princ "\n"))
       (princ "(custom-set-variables
-- 
2.20.1