bug#26923: 25.2; `setq-local': allow multiple assignments or add optional buffer arg

bug#26923: 25.2; `setq-local': allow multiple assignments or add optional buffer arg

[Drew Adams]

1. I believe this has been discussed before, and presumably the result
   (decision or lack of one) has been not to make the change, but I'd
   still suggest that `setq-local', like `setq', should allow multiple
   assignment pairs.

2. If that's definitely rejected then please consider this other
   enhancement instead: Allow a buffer argument:

   (setq-local VAR VALUE &optional BUFFER)

   This would be essentially just a convenience.

   See this emacs.SE question:
   https://emacs.stackexchange.com/q/32787/105

In GNU Emacs 25.2.1 (x86_64-w64-mingw32)
 of 2017-04-24
Windowing system distributor `Microsoft Corp.', version 6.1.7601
Configured using:
 `configure --without-dbus --without-compress-install 'CFLAGS=-O2
 -static -g3''

bug#26923: 25.2; `setq-local': allow multiple assignments or add optional buffer arg

[Lars Ingebrigtsen]

Drew Adams <drew.adams@oracle.com> writes:

> 1. I believe this has been discussed before, and presumably the result
>    (decision or lack of one) has been not to make the change, but I'd
>    still suggest that `setq-local', like `setq', should allow multiple
>    assignment pairs.

This was implemented by

Jordon Biondo <jordonbiondo@gmail.com>

but never applied.  Biondo has copyright assignment papers on file, but
apparently the final movement here was this email from Eli:

> > From: Jordon Biondo <jordonbiondo@gmail.com>
> > Date: Wed, 8 Feb 2017 10:59:19 -0500
> > Cc: John Wiegley <jwiegley@gmail.com>, Emacs development discussions
> > <emacs-devel@gnu.org>
> > 
> > My paperwork is now complete, if that's the only thing holding up this patch.
>
> Thanks.  Could you please re-submit your patch, and add to it suitable
> changes to NEWS and to the ELisp manual?

Eli, if you still think this is something that should be done, I can add
the NEWS entry and the manual changes.  I've re-spun the patch for the
current trunk:

diff --git a/lisp/subr.el b/lisp/subr.el
index e361b8324f..8cb8bcef69 100644
--- a/lisp/subr.el
+++ b/lisp/subr.el
@@ -143,11 +143,22 @@ setq-default
       (push `(set-default ',(pop args) ,(pop args)) exps))
     `(progn . ,(nreverse exps))))
 
-(defmacro setq-local (var val)
-  "Set variable VAR to value VAL in current buffer."
+(defmacro setq-local (&rest args)
+  "Set each SYM to the value of its VAL in the current buffer.
+
+\(fn [SYM VAL]...)"
   ;; Can't use backquote here, it's too early in the bootstrap.
   (declare (debug (symbolp form)))
-  (list 'set (list 'make-local-variable (list 'quote var)) val))
+  (let ((expr))
+    (while args
+      (setq expr
+            (cons
+             (list 'set
+                   (list 'make-local-variable (list 'quote (car args)))
+                   (car (cdr args)))
+             expr))
+      (setq args (cdr (cdr args))))
+    (cons 'progn (nreverse expr))))
 
 (defmacro defvar-local (var val &optional docstring)
   "Define VAR as a buffer-local variable with default value VAL.


-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#26923: 25.2; `setq-local': allow multiple assignments or add optional buffer arg

[Eli Zaretskii]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Date: Wed, 09 Oct 2019 10:15:49 +0200
> Cc: 26923@debbugs.gnu.org
> 
> > Thanks.  Could you please re-submit your patch, and add to it suitable
> > changes to NEWS and to the ELisp manual?
> 
> Eli, if you still think this is something that should be done, I can add
> the NEWS entry and the manual changes.

Yes, please, and thanks.

bug#26923: 25.2; `setq-local': allow multiple assignments or add optional buffer arg

[Robert Pluim]

>>>>> On Thu, 10 Oct 2019 13:33:34 +0300, Eli Zaretskii <eliz@gnu.org> said:

    >> From: Lars Ingebrigtsen <larsi@gnus.org>
    >> Date: Wed, 09 Oct 2019 10:15:49 +0200
    >> Cc: 26923@debbugs.gnu.org
    >> 
    >> > Thanks.  Could you please re-submit your patch, and add to it suitable
    >> > changes to NEWS and to the ELisp manual?
    >> 
    >> Eli, if you still think this is something that should be done, I can add
    >> the NEWS entry and the manual changes.

    Eli> Yes, please, and thanks.

Unlike 'setq', this new version of 'setq-local' does not enforce an
even number of arguments, so the last arg gets set to nil.

Robert

bug#26923: 25.2; `setq-local': allow multiple assignments or add optional buffer arg

[Eli Zaretskii]

> From: Robert Pluim <rpluim@gmail.com>
> Cc: Lars Ingebrigtsen <larsi@gnus.org>,  26923@debbugs.gnu.org
> Date: Thu, 10 Oct 2019 15:02:15 +0200
> 
> Unlike 'setq', this new version of 'setq-local' does not enforce an
> even number of arguments

Maybe it should, for consistency (less things to remember)?

bug#26923: 25.2; `setq-local': allow multiple assignments or add optional buffer arg

[Lars Ingebrigtsen]

Eli Zaretskii <eliz@gnu.org> writes:

>> Unlike 'setq', this new version of 'setq-local' does not enforce an
>> even number of arguments
>
> Maybe it should, for consistency (less things to remember)?

Yes, I think so.  I'll rework the patch to check for that.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#26923: 25.2; `setq-local': allow multiple assignments or add optional buffer arg

[Lars Ingebrigtsen]

Lars Ingebrigtsen <larsi@gnus.org> writes:

> Eli Zaretskii <eliz@gnu.org> writes:
>
>>> Unlike 'setq', this new version of 'setq-local' does not enforce an
>>> even number of arguments
>>
>> Maybe it should, for consistency (less things to remember)?
>
> Yes, I think so.  I'll rework the patch to check for that.

I've now done this, as well as updating the documentation and NEWS, and
I've made nntp.el use the new syntax (as a test case).

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no