Read input into string in Lisp reader macro -

i trying make reader macro convert @this "this". have:

(defun string-reader (stream char)    (declare (ignore char))    (format nil "\"~a\"" (read-line stream t nil t))    )     (set-macro-character #\@ #'string-reader ) 

the problem requires put newline after ever @this. i've tried (read), returns variable test, has not been set. can't hard-code number of characters after @ symbol, because don't know how many there be. there way fix this?

edit: way loop on read-char , peek-char, reading until #),#\space, or #\newline?

you can try use read , @ returns:

(defun string-reader (stream char)    (declare (ignore char))    (let ((this (let ((*readtable* (copy-readtable)))                  (setf (readtable-case *readtable*) :preserve)                  (read stream t nil t))))      (etypecase        (string this)        (symbol (symbol-name this)))))  (set-macro-character #\@ #'string-reader) 

above allow @this , @"this", not @333.

this version reads string until whitespace:

(defun read-as-string-until-whitespace (stream)   (with-output-to-string (out-stream)     (loop next = (peek-char nil stream t nil t)           until (member next '(#\space #\newline #\tab))           (write-char (read-char stream t nil t) out-stream))))  (defun string-reader (stream char)    (declare (ignore char))    (read-as-string-until-whitespace stream))  (set-macro-character #\@ #'string-reader) 

example:

cl-user 21 > @this "this"  cl-user 22 > @42 "42"  cl-user 23 > @foobar "foobar"