��的反引用和解引用。如果真想进一步提高宏技术的话，你可以尝试分析它的工作方式。如下所示：</p><pre class="pre codeblock lisp"><code>(defmacro once-only ((&amp;rest names) &amp;body body)
  (let ((gensyms (loop for n in names collect (gensym))))
    `(let (,@(loop for g in gensyms collect `(,g (gensym))))
      `(let (,,@(loop for g in gensyms for n in names collect ``(,,g ,,n)))
        ,(let (,@(loop for n in names for g in gensyms collect `(,n ,g)))
           ,@bo