These first four defcustoms behave as I expect.
The first has a default value of nil - empty alist. The second has a
default value of (("key1" :x ("a" "b") ("q"))). The third had a default
value of (("key1" :x () :w ("q"))) - one of the plist-entry values is
empty. The fourth has a default value of (("key1")) - empty plist.
The option should be an alist with elements that have a string key and a
plist value. Each plist element has a keyword key and a list of string
values. The alist can be empty, any plist can be empty, and any
plist-entry value can be empty.
;; OK
(defcustom myvar ()
"..."
:group 'emacs
:type '(alist :key-type (string :tag "Alist key (string):")
:value-type
(plist :key-type symbol
:options (:x :y :z)
:value-type (repeat string))))
;; OK
(defcustom myvar '(("key1" :x ("a" "b") :w ("q")))
"..."
:group 'emacs
:type '(alist :key-type (string :tag "Alist key (string):")
:value-type
(plist :key-type
(restricted-sexp :match-alternatives (keywordp)
:tag "Plist key (keyword)")
:options (:x :y :z)
:value-type (repeat string))))
;; OK
(defcustom myvar '(("key1" :x () :w ("q")))
"..."
:group 'emacs
:type '(alist :key-type (string :tag "Alist key (string):")
:value-type
(plist :key-type
(restricted-sexp :match-alternatives (keywordp)
:tag "Plist key (keyword)")
:options (:x :y :z)
:value-type (repeat string))))
;; OK
(defcustom myvar '(("key1"))
"..."
:group 'emacs
:type '(alist :key-type (string :tag "Alist key (string):")
:value-type
(plist :key-type
(restricted-sexp :match-alternatives (keywordp)
:tag "Plist key (keyword)")
:options (:x :y :z)
:value-type (repeat string))))
The first OK example specifies the type of the plist key as just symbol,
not as keywordp. But I want to constrain it to be a symbol that's a
keyword. The problem occurs when I try to do that AND I use a default
value of nil (see next).
This one is no good - that's the bug:
;; When click initial INS get prompted for a Lisp expression, get warnings,
;; and Customize buffer contents are changed to just INS DEL while prompting.
;;
(defcustom myvar ()
"..."
:group 'emacs
:type '(alist :key-type (string :tag "Alist key (string):")
:value-type
(plist :key-type
(restricted-sexp :match-alternatives (keywordp)
:tag "Plist key (keyword)")
:options (:x :y :z)
:value-type (repeat string))))
In this case the default value is nil, but the defcustom also specifies
the type of plist values as keywordp. I think this definition should
work fine. But when you click the sole INS button at the outset you're
prompted for a Lisp expression and you simultaneously get a warning that
a plist key is not of the right type. If you enter a Lisp expression
(e.g. just 42 or whatever) then the Customize buffer appears as it
should. I think (1) you shouldn't be prompted for anything and (2) you
shouln't get any warning of anything.
Warning (widget-bad-default-value):
A widget of type restricted-sexp has a bad default value.
value: nil
match function: widget-restricted-sexp-match
match-alternatives: (keywordp) Disable showing Disable logging
See attached screenshot, which shows the prompt as well as the
Customize buffer during prompting and the *Warnings* buffer.
In GNU Emacs 28.2 (build 2, x86_64-w64-mingw32)
of 2022-09-13 built on AVALON
Windowing system distributor 'Microsoft Corp.', version 10.0.19044
System Description: Microsoft Windows 10 Pro (v10.0.2009.19044.2251)
Configured using:
'configure --with-modules --without-dbus --with-native-compilation
--without-compress-install CFLAGS=-O2'
Configured features:
ACL GIF GMP GNUTLS HARFBUZZ JPEG JSON LCMS2 LIBXML2 MODULES NATIVE_COMP
NOTIFY W32NOTIFY PDUMPER PNG RSVG SOUND THREADS TIFF TOOLKIT_SCROLL_BARS
XPM ZLIB
(NATIVE_COMP present but libgccjit not available)
throw-emacs-defcustom-bug.png
Description: throw-emacs-defcustom-bug.png
--- End Message ---