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10.2.14 symbol-value [Accessor]

symbol-value symbol ⇒ value

(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.