(defgroup sly-ui nil
"Interaction with the Superior Lisp Environment."
:prefix "sly-"
:group 'sly)
(defcustom sly-truncate-lines t
"Set `truncate-lines' in popup buffers.
This applies to buffers that present lines as rows of data, such as
debugger backtraces and apropos listings."
:type 'boolean
:group 'sly-ui)
(defcustom sly-kill-without-query-p nil
"If non-nil, kill SLY processes without query when quitting Emacs.
This applies to the *inferior-lisp* buffer and the network connections."
:type 'boolean
:group 'sly-ui)
;;===========
(get 'sly-ui 'custom-group)
;; => ((sly-truncate-lines custom-variable) (sly-kill-without-query-p custom-variable))
看了下源碼研究出來的。
defcustom 用了 custom-declare-variable，后者用 custom-add-to-group 來加变量名到 Group，实貭是个 put，所以用 get 就能看 Group 下的 Custom 項。
Update 有現成的 function custom-group-members