fboundp

fboundp Function

Syntax:

fboundp name → generalized-boolean

Pronunciation:

[ ef ba_undp—e ]

Arguments and Values:

name—a function name.

generalized-boolean—a generalized boolean.

Description:

Returns true if name is fbound; otherwise, returns false.

Examples:

(fboundp ’car) → true 
(fboundp ’nth-value) → false 
(fboundp ’with-open-file) → true 
(fboundp ’unwind-protect) → true 
(defun my-function (x) x) → MY-FUNCTION 
(fboundp ’my-function) → true 
(let ((saved-definition (symbol-function ’my-function))) 
  (unwind-protect (progn (fmakunbound ’my-function) 
			 (fboundp ’my-function)) 
    (setf (symbol-function ’my-function) saved-definition))) 
→ false 
(fboundp ’my-function) → true 
(defmacro my-macro (x) ‘’,x) → MY-MACRO 
(fboundp ’my-macro) → true 
(fmakunbound ’my-function) → MY-FUNCTION 
(fboundp ’my-function) → false 
(flet ((my-function (x) x)) 
  (fboundp ’my-function)) → false 

Exceptional Situations:

Should signal an error of type type-error if name is not a function name.

See Also:

symbol-function, fmakunbound, fdefinition

Notes:

It is permissible to call symbol-function on any symbol that is fbound.

fboundp is sometimes used to “guard” an access to the function cell, as in: (if (fboundp x) (symbol-function x))

Defining a setf expander F does not cause the setf function (setf F) to become defined.

Expanded Reference: fboundp

tip

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(fboundp )