我有一個CLOS對象的位置的名稱的列表:CLOS插槽存取:讀不能寫
(DEFCLASS TRIAL-DATA (STANDARD-OBJECT)
((A-DATUM :ACCESSOR A-DATUM :INITARG :A-DATUM :INITFORM NIL)
(BOTH-DATA :ACCESSOR BOTH-DATA :INITARG :BOTH-DATA :INITFORM 0)
(CUMULATIVE-DATA :ACCESSOR CUMULATIVE-DATA :INITARG :CUMULATIVE-DATA :INITFORM NIL)
(NAME :ACCESSOR NAME :INITARG :NAME :INITFORM VALUE)))
(let* ((td (make-instance 'trial-data))
(slot-lst (mapcar #'slot-definition-name (class-slots (class-of td)))))
我可以讀取這些插槽的值:
(let* ((td (make-instance 'trial-data))
(slot-lst (mapcar #'slot-definition-name (class-slots (class-of td)))))
(funcall (symbol-function (nth 0 slot-lst)) td))
== >無
但爲什麼我不能向這些插槽寫入新值?我的班級定義的試用數據是否應該爲每個插槽創建一個訪問函數?
;; Should set the first slot, a-datum's, value to 42
(let* ((td (make-instance 'trial-data))
(slot-lst (mapcar #'slot-definition-name (class-slots (class-of td)))))
(setf (funcall (symbol-function (nth 0 slot-lst)) td) 42))
==>
;Compiler warnings for "/Users/frank/Documents/NRL/Error/Patrolbot/Patrol Construction Notes & Testing.lisp" :
; In an anonymous lambda form at position 123: Undefined function (SETF FUNCALL)
> Error: Undefined function (SETF FUNCALL) called with arguments (42 #<STANDARD-GENERIC-FUNCTION A-DATUM #x302001D1C5DF> #<TRIAL-DATA #x30200200D95D>) .
> While executing: #<Anonymous Function #x30200200EB7F>, in process Listener-2(5).
所以,你可以用'(mapcar#'插槽定義名稱(類插槽(TD類的)))'和'(SETF插槽值)一起'並通過索引讀取/寫入插槽的數據。 – Mark