symbol-value (Accessor)

Syntax:

(setf (symbol-value symbol) new-value)

Arguments and Values:

symbol—a symbol that must have a value.

value, new-value—an object.

Description:

Accesses the symbol's value cell.

Examples:

 (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

Affected By:

makunbound, set, setq

Exceptional Situations:

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.)

See Also:

boundp, makunbound, set, setq

Notes:

symbol-value can be used to get the value of a constant variable. symbol-value cannot access the value of a lexical variable.