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bug#35546: 27.0.50; setf return value for new alist entries is wrong
From: |
Michael Heerdegen |
Subject: |
bug#35546: 27.0.50; setf return value for new alist entries is wrong |
Date: |
Tue, 07 May 2019 13:19:54 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/27.0.50 (gnu/linux) |
Tassilo Horn <tsdh@gnu.org> writes:
> According to the last sentence, I'd assume that
>
> (setq my-alist nil)
> (setf (alist-get 'foo my-alist) "foo-value")
>
> would return "foo-value", but infact it returns ((foo . "foo-value")).
> As soon as there is an association for 'foo, it returns the new value,
> i.e., "foo-value".
I agree. I think fixing should be quite straightforward:
From 2fc149e3afa411f5b64c743de362378568f97bd6 Mon Sep 17 00:00:00 2001
From: Michael Heerdegen <michael_heerdegen@web.de>
Date: Mon, 6 May 2019 14:58:24 +0200
Subject: [PATCH] Fix alist-get gv setter not returning VAL
This fixes Bug#35546.
* lisp/emacs-lisp/gv.el (alist-get): Make setter return the set value
to preserve 'setf' semantics.
---
lisp/emacs-lisp/gv.el | 26 ++++++++++++++------------
1 file changed, 14 insertions(+), 12 deletions(-)
diff --git a/lisp/emacs-lisp/gv.el b/lisp/emacs-lisp/gv.el
index 4ea3ce84fc..bdd1574820 100644
--- a/lisp/emacs-lisp/gv.el
+++ b/lisp/emacs-lisp/gv.el
@@ -392,18 +392,20 @@ setf
,(funcall setter
`(cons (setq ,p (cons ,k ,v))
,getter)))))
- (cond
- ((null remove) set-exp)
- ((or (eql v default)
- (and (eq (car-safe v) 'quote)
- (eq (car-safe default) 'quote)
- (eql (cadr v) (cadr default))))
- `(if ,p ,(funcall setter `(delq ,p ,getter))))
- (t
- `(cond
- ((not (eql ,default ,v)) ,set-exp)
- (,p ,(funcall setter
- `(delq ,p ,getter)))))))))))))))
+ `(progn
+ ,(cond
+ ((null remove) set-exp)
+ ((or (eql v default)
+ (and (eq (car-safe v) 'quote)
+ (eq (car-safe default) 'quote)
+ (eql (cadr v) (cadr default))))
+ `(if ,p ,(funcall setter `(delq ,p ,getter))))
+ (t
+ `(cond
+ ((not (eql ,default ,v)) ,set-exp)
+ (,p ,(funcall setter
+ `(delq ,p ,getter))))))
+ ,v))))))))))
;;; Some occasionally handy extensions.
--
2.20.1
Michael.