symbol-value symbol ⇒ value
(setf ( symbol-value symbol) new-value)
Accesses the symbol’s value cell.
(setf (symbol-value 'a) 1) ⇒ 1
(symbol-value 'a) ⇒ 1
;; SYMBOL-VALUE cannot see lexical variables.
(let ((a 2)) (symbol-value 'a)) ⇒ 1
(let ((a 2)) (setq a 3) (symbol-value 'a)) ⇒ 1
;; SYMBOL-VALUE can see dynamic variables.
(let ((a 2))
(declare (special a))
(symbol-value 'a)) ⇒ 2
(let ((a 2))
(declare (special a))
(setq a 3)
(symbol-value 'a)) ⇒ 3
(let ((a 2))
(setf (symbol-value 'a) 3)
a) ⇒ 2
a ⇒ 3
(symbol-value 'a) ⇒ 3
(let ((a 4))
(declare (special a))
(let ((b (symbol-value 'a)))
(setf (symbol-value 'a) 5)
(values a b))) ⇒ 5, 4
a ⇒ 3
(symbol-value :any-keyword) ⇒ :ANY-KEYWORD
(symbol-value 'nil) ⇒ NIL
(symbol-value '()) ⇒ NIL
;; The precision of this next one is implementation-dependent.
(symbol-value 'pi) ⇒ 3.141592653589793d0
Should signal an error of type type-error if symbol is not a symbol.
Should signal unbound-variable if symbol is unbound and an attempt is made to read its value. (No such error is signaled on an attempt to write its value.)
boundp, makunbound, set, setq
symbol-value can be used to get the value of a constant variable. symbol-value cannot access the value of a lexical variable.