Subject: bug#66938: 30.0.50 [PATCH]: Make EIEIO :accessor behave like :reader when reading a slot's value

From: João Távora <[email-masked]>
Date: Wed, 29 Nov 2023 16:09:23 +0000

On Wed, Nov 29, 2023 at 3:47 PM Stefan Monnier <[email-masked]> wrote:

> diff --git a/lisp/emacs-lisp/eieio-core.el b/lisp/emacs-lisp/eieio-core.el
> index a394156c93a..37c5ebdb6da 100644
> --- a/lisp/emacs-lisp/eieio-core.el
> +++ b/lisp/emacs-lisp/eieio-core.el
> @@ -951,7 +951,10 @@ eieio-set-defaults
>    (let ((slots (eieio--class-slots (eieio--object-class obj))))
>      (dotimes (i (length slots))
>        (let* ((name (cl--slot-descriptor-name (aref slots i)))
> -             (df (eieio-oref-default obj name)))
> +             ;; If the `:initform` signals an error, just skip it,
> +             ;; since the error is intended to be signal'ed from
> +             ;; `initialize-instance` rather than at the time of `defclass`.
> +             (df (ignore-errors (eieio-oref-default obj name))))
>          (if (or df set-all)
>              (eieio-oset obj name df))))))
>

So the initform  is evaluated twice now, once with errors
shooshed?  What about side effects? (I know, a terrible idea,
but still...) Can't we just not eval it at defclass time?

João