I have encountered the following confusing behavior (and 'regression'
compared to Emacs 27).
Starting from emacs -Q, in Emacs 27 when I try to evaluate the following code:
(require 'eieio)
(defclass rectangle ()
(height width))
different than in CLOS, Emacs errors with:
'(wrong-type-argument listp height)'
When I evaluate the same code in Emacs 28 then Emacs does not return an
error.
However, if I subsequently try to initialize the slots using:
(let ((r (make-instance rectangle)))
(setf (slot-value r 'height) 2
(slot-value r 'width) 3))
then Emacs 28 does return an error. If I replace the code to create the
class with (adding the parentheses around the slots):
(defclass rectangle ()
((height) (width)))
then the code above for initializing the slots works as expected (and similar behavior when using oref). Which means that also in Emacs 28 the parentheses are required. So Emacs 27 correctly errors when not using them, but Emacs 28 suggests that things are alright when omitting the parentheses which is incorrect and confusing.
Then additionally, the requirement of the parentheses is, as far as I
could find, not explicitly mentioned as a 'difference from CLOS' in the manual, which 'additionlly' is confusing.
In GNU Emacs 28.0.50 (build 3, x86_64-pc-linux-gnu, GTK+ Version 3.24.30, cairo version 1.17.4)
of 2021-09-06 built on daniel-fedora
Repository revision: c4724add006e62b81f847937db56335a81bdcc74
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12011000
System Description: Fedora 34 (Workstation Edition)
Configured using:
'configure --with-mailutils --with-cairo --with-modules --with-pgtk
--with-native-compilation'
Configured features:
ACL CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GPM GSETTINGS HARFBUZZ JPEG
JSON LCMS2 LIBOTF LIBSELINUX LIBSYSTEMD LIBXML2 M17N_FLT MODULES
NATIVE_COMP NOTIFY INOTIFY PDUMPER PNG RSVG SECCOMP SOUND THREADS TIFF
TOOLKIT_SCROLL_BARS X11 XDBE XIM XPM GTK3 ZLIB
Important settings:
value of $LANG: en_US.UTF-8
value of $XMODIFIERS: @im=none
locale-coding-system: utf-8-unix
Major mode: Lisp Interaction
Minor modes in effect:
tooltip-mode: t
global-eldoc-mode: t
eldoc-mode: t
electric-indent-mode: t
mouse-wheel-mode: t
tool-bar-mode: t
menu-bar-mode: t
file-name-shadow-mode: t
global-font-lock-mode: t
font-lock-mode: t
blink-cursor-mode: t
auto-composition-mode: t
auto-encryption-mode: t
auto-compression-mode: t
line-number-mode: t
indent-tabs-mode: t
transient-mark-mode: t
Load-path shadows:
None found.
Features:
(shadow sort mail-extr emacsbug message rmc puny dired dired-loaddefs
rfc822 mml mml-sec epa derived epg rfc6068 epg-config gnus-util rmail
rmail-loaddefs auth-source password-cache json map text-property-search
seq mm-decode mm-bodies mm-encode mail-parse rfc2231 mailabbrev
gmm-utils mailheader sendmail rfc2047 rfc2045 ietf-drums mm-util
mail-prsvr mail-utils help-fns radix-tree cl-print debug backtrace
help-mode find-func cl-seq eieio byte-opt bytecomp byte-compile cconv
eieio-core cl-macs gv eieio-loaddefs time-date subr-x cl-loaddefs cl-lib
iso-transl tooltip eldoc electric uniquify ediff-hook vc-hooks
lisp-float-type mwheel term/x-win x-win term/common-win x-dnd tool-bar
dnd fontset image regexp-opt fringe tabulated-list replace newcomment
text-mode elisp-mode lisp-mode prog-mode register page tab-bar menu-bar
rfn-eshadow isearch easymenu timer select scroll-bar mouse jit-lock
font-lock syntax font-core term/tty-colors frame minibuffer cl-generic
cham georgian utf-8-lang misc-lang vietnamese tibetan thai tai-viet lao
korean japanese eucjp-ms cp51932 hebrew greek romanian slovak czech
european ethiopic indian cyrillic chinese composite charscript charprop
case-table epa-hook jka-cmpr-hook help simple abbrev obarray
cl-preloaded nadvice button loaddefs faces cus-face macroexp files
window text-properties overlay sha1 md5 base64 format env code-pages
mule custom widget hashtable-print-readable backquote threads dbusbind
inotify lcms2 dynamic-setting system-font-setting font-render-setting
cairo move-toolbar gtk x-toolkit x multi-tty make-network-process
native-compile emacs)
Memory information:
((conses 16 74940 7555)
(symbols 48 7056 0)
(strings 32 21134 1155)
(string-bytes 1 724821)
(vectors 16 13991)
(vector-slots 8 277232 15363)
(floats 8 26 33)
(intervals 56 281 0)
(buffers 992 13))