●语法设定:
fboundp name => generalized-boolean
●发音：
[,ef'bandpee]
●参数和值:
name---a function name.
generalized-boolean---a generalized boolean.
●详情:
Returns true if name is fbound; otherwise, returns false.
●例子:
(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
●副作用: None.
●受制于： 无。
●例外情况：
Should signal an error of type type-error if name is not a function name.
●更多信息:
symbol-function, fmakunbound, fdefinition
●说明:
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.