From: Stefan Monnier <monnier@iro.umontreal.ca>
To: emacs-devel@gnu.org
Subject: Re: custom-set-variables considered harmful
Date: Mon, 04 Dec 2017 08:48:06 -0500 [thread overview]
Message-ID: <jwvo9nefvzv.fsf-monnier+emacs@gnu.org> (raw)
In-Reply-To: <jwv7euup2ql.fsf-monnier+emacs@gnu.org> (Stefan Monnier's message of "Mon, 13 Nov 2017 11:26:29 -0500")
> Here's a sample patch to do that. Comments?
Based on the feedback, I added a config var to control the use of `setq'.
I also added a backward compatibility hack which makes it so that your
"new style config" will partly work in Emacs<27.
Any objection to installing the patch below into `master`?
Stefan
diff --git a/lisp/cus-edit.el b/lisp/cus-edit.el
index 4965adfd56..d7166294c2 100644
--- a/lisp/cus-edit.el
+++ b/lisp/cus-edit.el
@@ -4374,6 +4382,23 @@ custom-file
if only the first line of the docstring is shown."))
:group 'customize)
+(defcustom custom-mimic-plain-elisp nil
+ "If non-nil, save user settings with the new format.
+This new format tries to mimick the code that would be written by hand
+in plain Elisp. But it relies on `custom-autogenerated-user-settings' which
+is a new macro in Emacs-27, so settings saved with this will not work
+reliably in Emacs<27 (although a backward compatibility trick is used
+which should make them work to some extent)."
+ :type 'boolean
+ :group 'customize)
+
+(defcustom custom-mimic-plain-elisp-use-setq nil
+ "If non-nil, use `setq' when possible in generated code.
+If nil, `custom-mimic-plain-elisp' will only use `customize-set-variable',
+which is the more reliable option."
+ :type 'boolean
+ :group 'customize)
+
(defun custom-file (&optional no-error)
"Return the file name for saving customizations."
(if (or (null user-init-file)
@@ -4501,10 +4526,32 @@ custom-save-delete
(defvar sort-fold-case) ; defined in sort.el
+(defun custom--mimic-plain-elisp (symbol exp requests comment)
+ "Print the code corresponding to setting SYMBOL to EXP."
+ ;; Do the inverse conversion of custom-autogenerated-user-settings.
+ (let* ((e (cond
+ ((eq (get symbol 'custom-set) #'custom-set-minor-mode)
+ `(,symbol ,(if (memq exp '(t nil))
+ (if exp 1 -1)
+ '(if ,exp 1 -1))))
+ ((or (not custom-mimic-plain-elisp-use-setq)
+ (get symbol 'custom-set))
+ `(customize-set-variable ',symbol ,exp))
+ ((local-variable-if-set-p
+ symbol (get-buffer-create "*scratch*"))
+ `(setq-default ,symbol ,exp))
+ (t `(setq ,symbol ,exp)))))
+ (dolist (e (nconc (mapcar (lambda (r) `(require ',r)) requests)
+ (if comment (list comment e) (list e))))
+ (princ " ")
+ (pp e)
+ (unless (bolp) (princ "\n")))))
+
(defun custom-save-variables ()
"Save all customized variables in `custom-file'."
(save-excursion
(custom-save-delete 'custom-set-variables)
+ (custom-save-delete 'custom-autogenerated-user-settings)
(let ((standard-output (current-buffer))
(saved-list (make-list 1 0))
sort-fold-case)
@@ -4519,8 +4566,21 @@ custom-save-variables
(setq saved-list (sort (cdr saved-list) 'string<))
(unless (bolp)
(princ "\n"))
- (princ "(custom-set-variables
- ;; custom-set-variables was added by Custom.
+ (when (and custom-mimic-plain-elisp
+ (not (save-excursion
+ (re-search-backward
+ "custom-autogenerated-user-settings" nil t))))
+ (princ ";; Backward compatibility definition for Emacs<27")
+ (princ ";; auto-added by `custom-save-variables'.\n")
+ (pp '(unless (fboundp 'custom-autogenerated-user-settings)
+ (defalias 'custom-autogenerated-user-settings 'progn)))
+ (unless (bolp) (princ "\n")))
+ (princ (if custom-mimic-plain-elisp
+ "(custom-autogenerated-user-settings
+ ;; This custom-autogenerated-user-settings was added by Custom."
+ "(custom-set-variables
+ ;; This custom-set-variables was added by Custom."))
+ (princ "
;; If you edit it by hand, you could mess it up, so be careful.
;; Your init file should contain only one such instance.
;; If there is more than one, they won't work right.\n")
@@ -4555,6 +4555,8 @@
;; with the customize facility.
(unless (bolp)
(princ "\n"))
+ (if custom-mimic-plain-elisp
+ (custom--mimic-plain-elisp symbol (car value) requests comment)
(princ " '(")
(prin1 symbol)
(princ " ")
@@ -4576,7 +4578,7 @@
(when comment
(princ " ")
(prin1 comment))))
- (princ ")"))))
+ (princ ")")))))
(if (bolp)
(princ " "))
(princ ")")
diff --git a/lisp/custom.el b/lisp/custom.el
index 352fc6bd53..b641740266 100644
--- a/lisp/custom.el
+++ b/lisp/custom.el
@@ -1,4 +1,4 @@
-;;; custom.el --- tools for declaring and initializing options
+;;; custom.el --- tools for declaring and initializing options -*- lexical-binding:t -*-
;;
;; Copyright (C) 1996-1997, 1999, 2001-2017 Free Software Foundation,
;; Inc.
@@ -926,6 +933,36 @@ custom-fix-face-spec
(nreverse result))
spec)))
\f
+(defmacro custom-autogenerated-user-settings (&rest body)
+ "Install user customizations of variable values specified in ARGS.
+Expect the format output by `custom-save-variables'."
+ (let* ((settings '())
+ (requests '())
+ (comment nil)
+ (mk (lambda (x e)
+ (push
+ `'(,x ,e
+ . ,(when (or comment requests)
+ `(nil ,(prog1 (nreverse requests)
+ (setq requests '()))
+ . ,(when comment
+ (prog1 (list comment)
+ (setq comment nil))))))
+ settings))))
+ (dolist (e body)
+ (pcase e
+ (`(,(or 'setq 'setq-default) ,x ,e) (funcall mk x e))
+ (`(require ',p) (push p requests))
+ (`(customize-set-variable ',x ,e) (funcall mk x e))
+ (`(,x ,(and v (or 1 -1))) (funcall mk x (> v 0)))
+ (`(,x (if ,e 1 -1)) (funcall mk x e))
+ ((pred stringp)
+ (and comment (message "Dropping extra comment: %S" comment))
+ (setq comment e))
+ (_
+ (message "Unrecognized expression in custom-autogenerated-user-settings: %S" e))))
+ `(custom-set-variables ,@(nreverse settings))))
+
(defun custom-set-variables (&rest args)
"Install user customizations of variable values specified in ARGS.
These settings are registered as theme `user'.
next prev parent reply other threads:[~2017-12-04 13:48 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-04 17:10 custom-set-variables considered harmful Stefan Monnier
2017-11-06 9:02 ` Philippe Vaucher
2017-11-06 12:19 ` Clément Pit-Claudel
2017-11-06 16:36 ` raman
2017-11-07 19:53 ` Stefan Monnier
2017-11-08 10:06 ` Vivek Dasmohapatra
2017-11-08 13:38 ` Stefan Monnier
2017-11-08 14:23 ` Vivek Dasmohapatra
2017-11-08 15:17 ` Stefan Monnier
2017-11-08 15:34 ` Vivek Dasmohapatra
2017-11-13 16:26 ` Stefan Monnier
2017-11-24 7:04 ` Elias Mårtenson
2017-11-24 7:16 ` Stefan Monnier
2017-11-24 17:37 ` Clément Pit-Claudel
2017-11-24 17:56 ` Stefan Monnier
2017-11-26 12:15 ` Elias Mårtenson
2017-11-26 16:30 ` Drew Adams
2017-11-28 14:12 ` Philippe Vaucher
2017-11-28 16:50 ` John Wiegley
2017-12-01 9:44 ` Philippe Vaucher
2017-11-29 3:36 ` Elias Mårtenson
2017-11-29 15:00 ` Stefan Monnier
2017-11-29 15:03 ` Drew Adams
2017-12-01 20:42 ` Robert Weiner
2017-12-02 0:10 ` Richard Stallman
2017-12-02 1:58 ` Drew Adams
2017-12-02 5:56 ` Teemu Likonen
2017-11-29 16:35 ` Elias Mårtenson
2017-11-29 19:57 ` Scott Randby
2017-11-29 22:08 ` Stefan Monnier
2017-11-30 0:40 ` Scott Randby
2017-12-01 9:51 ` Philippe Vaucher
2017-12-04 13:48 ` Stefan Monnier [this message]
2017-12-04 15:36 ` Eli Zaretskii
2017-12-04 16:05 ` Robert Weiner
2017-12-04 23:50 ` Richard Stallman
2017-12-05 1:45 ` Stefan Monnier
2017-11-23 20:12 ` John Wiegley
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