From: Eli Zaretskii <eliz@gnu.org>
To: Brandon Irizarry <brandon.irizarry@gmail.com>,
Stefan Monnier <monnier@iro.umontreal.ca>
Cc: 66938@debbugs.gnu.org
Subject: bug#66938: 30.0.50 [PATCH]: Make EIEIO :accessor behave like :reader when reading a slot's value
Date: Sat, 11 Nov 2023 12:21:23 +0200 [thread overview]
Message-ID: <83leb4wpy4.fsf@gnu.org> (raw)
In-Reply-To: <CAJm+nuELwm8qs+EDCyC1bJp8UpujTRjEeHTHNwBuyj2t7JnmNQ@mail.gmail.com> (message from Brandon Irizarry on Sat, 4 Nov 2023 18:03:06 -0400)
Stefan, any comments?
> From: Brandon Irizarry <brandon.irizarry@gmail.com>
> Date: Sat, 4 Nov 2023 18:03:06 -0400
>
> I've included a suggested patch for 'eieio.el', which slightly
> modifies the behavior of EIEIO's 'defclass'. When playing around with
> 'eieio-instance-inheritor' as a base class, I noticed that calls to
> the accessor (when used as a getter) weren't delegating to the parent
> instance (as defined when calling 'clone'). That is, an object clone that doesn't set
> its fields directly will report 'nil' when the accessor method is used as a getter for some slot.
>
> However, neither 'oref' nor ':reader' methods share this problem.
>
> The included patch duplicates the code for the reader method defined for
> the ':reader' case. In particular, it removes the 'slot-unboundp' check, which appeared
> to be the real culprit here. I've also deleted the FIXME comment which asked, "Why is this
> different from the :reader case?" since it no longer differs from it.
>
> There is some more context provided (along with an example) in the
> commit message included in the patch, in case it helps.
>
> I know this isn't earth-shattering, but I couldn't help but notice the issue;
> and, at least to me, it seemed like incorrect behavior. (Otherwise, in order to
> obtain the delegation behavior for a given slot, I'd be forced to define
> ':reader' and ':writer' separately, which feels rather verbose, given we have ':accessor'
> for this exact purpose.)
>
> - Brandon
>
>
> From 2d40d63d8738dc44b02ca61843fa61956958e84e Mon Sep 17 00:00:00 2001
> From: Brandon <brandon.irizarry@gmail.com>
> Date: Sat, 4 Nov 2023 17:11:32 -0400
> Subject: [PATCH] Make EIEIO ':accessor' behave like ':reader' when reading
>
> * lisp/emacs-lisp/eieio.el (defclass): Remove 'slot-boundp' check for
> :accessor's getter
>
> Clones of instances of subclasses of 'eieio-instance-inheritor' don't
> delegate to their ':parent-instance' field when reading object fields
> using ':accessor'.
>
> Say I have this code:
>
> (defclass foo (eieio-instance-inheritor)
> ((x :initarg :x
> :accessor ref-x
> :reader get-x)))
>
> (setq obj1 (foo :x 4)) ; #s(foo eieio--unbound 4)
> (setq obj2 (clone obj1)) ; #s(foo #s(foo eieio--unbound 4) eieio--unbound)
>
> (ref-x obj1) ; 4, which is correct.
> (ref-x obj2) ; nil. This is what we want to fix.
> (get-x obj2) ; Gives us 4: access via the reader performs delegation.
>
> My impression is that ':accessor' should behave as if ':reader' and
> ':writer' had been provided separately.
>
> With this patch, '(ref-x obj2)' now uses the exact same method as
> ':reader', and so would give us 4, as desired.
> ---
> lisp/emacs-lisp/eieio.el | 5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/lisp/emacs-lisp/eieio.el b/lisp/emacs-lisp/eieio.el
> index 39a5fd5b19c..8224606ec57 100644
> --- a/lisp/emacs-lisp/eieio.el
> +++ b/lisp/emacs-lisp/eieio.el
> @@ -213,9 +213,8 @@ defclass
> ,(internal--format-docstring-line
> "Retrieve the slot `%S' from an object of class `%S'."
> sname name)
> - ;; FIXME: Why is this different from the :reader case?
> - (if (slot-boundp this ',sname) (eieio-oref this ',sname)))
> - accessors)
> + (slot-value this ',sname))
> + accessors)
> (when (and eieio-backward-compatibility (eq alloc :class))
> ;; FIXME: How could I declare this *method* as obsolete.
> (push `(cl-defmethod ,acces ((this (subclass ,name)))
> --
> 2.39.2
>
next prev parent reply other threads:[~2023-11-11 10:21 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-04 22:03 bug#66938: 30.0.50 [PATCH]: Make EIEIO :accessor behave like :reader when reading a slot's value Brandon Irizarry
2023-11-11 10:21 ` Eli Zaretskii [this message]
2023-11-25 9:28 ` Eli Zaretskii
2023-11-25 14:56 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-11-26 3:21 ` Brandon Irizarry
2023-11-26 13:52 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-11-29 0:29 ` João Távora
2023-11-29 14:01 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-11-29 14:36 ` João Távora
2023-11-29 15:46 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-11-29 16:09 ` João Távora
2023-11-29 16:36 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-11-29 2:01 ` bug#66938: 30.0.50; Commit 6c47931a1ad4de ("Make EIEIO ':accessor' behave like ':reader' when reading (bug#66938)") breaks Eglot Arsen Arsenović via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-11-29 15:01 ` João Távora
2023-11-29 15:25 ` Arsen Arsenović via Bug reports for GNU Emacs, the Swiss army knife of text editors
2023-11-29 15:43 ` João Távora
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