* bug#12813: gv-define-simple-setter can evaluate VAL more than once
@ 2012-11-06 7:47 Glenn Morris
2012-11-07 3:39 ` Stefan Monnier
0 siblings, 1 reply; 2+ messages in thread
From: Glenn Morris @ 2012-11-06 7:47 UTC (permalink / raw)
To: 12813
Package: emacs
Version: 24.2.50
I don't know if you will consider this a bug.
gv-define-simple-setter with FIX-RETURN non-nil evaluates VAL twice.
This may lead to unintended behaviour.
Artificial example in `emacs -Q':
(defun foo (x)
(car x))
(defun foo-set (x y)
(setcar x y))
(gv-define-simple-setter foo foo-set t)
(setq bar '(1 2 3))
(setq i 0)
(setf (foo bar) (setq i (1+ i))) ; -> 1
bar ; -> (2 2 3) rather than (1 2 3)
defsetf in 24.2 was documented to not have this issue
(info "(cl)Customizing Setf")
[...]
(let ((temp VALUE))
(UPDATE-FN ARG1 ARG2 ARG3 temp)
temp)
So at the very least this will be relevant if http://debbugs.gnu.org/12812
gets the "obvious" fix.
^ permalink raw reply [flat|nested] 2+ messages in thread
* bug#12813: gv-define-simple-setter can evaluate VAL more than once
2012-11-06 7:47 bug#12813: gv-define-simple-setter can evaluate VAL more than once Glenn Morris
@ 2012-11-07 3:39 ` Stefan Monnier
0 siblings, 0 replies; 2+ messages in thread
From: Stefan Monnier @ 2012-11-07 3:39 UTC (permalink / raw)
To: Glenn Morris; +Cc: 12813
> I don't know if you will consider this a bug.
> gv-define-simple-setter with FIX-RETURN non-nil evaluates VAL twice.
Thanks, should be fixed now,
Stefan
^ permalink raw reply [flat|nested] 2+ messages in thread
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2012-11-06 7:47 bug#12813: gv-define-simple-setter can evaluate VAL more than once Glenn Morris
2012-11-07 3:39 ` Stefan Monnier
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