我如何要求Lisp编译器忽略(标签种类)函数？

Question

我盯着斯蒂尔的Common Lisp the Language,直到我脸色苍白,仍然有这个问题.如果我编译:

(defun x ()
  (labels ((y ()))
    5))
(princ (x))
(terpri)

有时候是这样的:

home:~/clisp/experiments$ clisp -c -q x.lisp
;; Compiling file /u/home/clisp/experiments/x.lisp ...
WARNING in lines 1..3 :
function X-Y is not used.
Misspelled or missing IGNORE declaration?
;; Wrote file /u/home/clisp/experiments/x.fas
0 errors, 1 warning
home:~/clisp/experiments$ 

很公平.那么我如何要求编译器忽略函数y？我试过这个:

(defun x ()
  (labels (#+ignore(y ()))
    5))
(princ (x))
(terpri)

它工作:

home:~/clisp/experiments$ clisp -c -q y.lisp
;; Compiling file /u/home/clisp/experiments/y.lisp ...
;; Wrote file /u/home/clisp/experiments/y.fas
0 errors, 0 warnings
home:~/clisp/experiments$ 

但不知何故,我不认为这是警告暗示我做的事情.

我该怎么办？

Answer 1

GNU CLISP要求你declare的函数被ignore剐.

(defun x ()
  (labels ((y ()))
    (declare (ignore (function y)))
    5))

或者(特别是如果这是宏扩展的结果,它取决于用户是否y实际使用),

(defun x ()
  (labels ((y ()))
    (declare (ignorable (function y)))
    5))

(无论您希望写什么(function y),您都可以自由地使用读者缩写#'y.)