with-gethash-accessors.lisp

(defmacro with-gethash-accessors (bindings &body body)
  `(macrolet ,(mapcar (lambda (b)
                        (if (symbolp b)
                            (let ((sym (gensym))
                                  (keyword (intern (string b) :keyword)))
                              `(,b (,sym) `(gethash ,,keyword ,,sym))))) bindings)
     ,@body))

;; target input:
(with-gethash-accessors (x y)
  (x object)
  (y object))

;; desired output:
(macrolet ((x (#:gensym1) `(gethash :x ,#:gensym1))
           (y (#:gensym2) `(gethash :y ,#:gensym2)))
  (x object)
  (y object))

;; actual output:
(macrolet ((x (#:gensym1) `(gethash ,:x ,#:gensym1))
           (y (#:gensym2) `(gethash ,:y ,#:gensym2)))
  (x object)
  (y object))

(defmacro with-gethash-accessors (bindings &body body)
  `(macrolet ,(loop with obj = (gensym "OBJECT")
                    for var in bindings
                    for key = (intern (string var) :keyword)
                    collect `(,var (,obj) `(gethash ,',key ,,obj)))
     ,@body))

flet version

(defmacro with-gethash-accessors (bindings &body body)
  `(flet ,(loop with obj = (gensym "OBJECT")
                with val = (gensym "VALUE")
                for var in bindings
                for key = (intern (string var) :keyword)
                collect `(,var (,obj) (gethash ',key ,obj))
                collect `((setf ,var) (,val ,obj) (setf (gethash ',key ,obj) ,val)))
     ,@body))