(defparameter *my-readtable* (copy-readtable))

(defun my-sharp-dot-reader (stream &rest _)
  (declare (ignore _))
  (let ((expr (read stream)))
    (list 'quote expr)))

(let ((*readtable* *my-readtable*))
  (set-dispatch-macro-character #\# #\. #'my-sharp-dot-reader))

(defun safe-read ()
  (let ((*readtable* *my-readtable*))
    (read)))

(setf b (safe-read))
(princ b)