;; idea here is to wrap a pointer with a type so we can avoid passing a pointer to a foo to something that expects a bar

(cffi:define-foreign-type pointer-wrapper ()
  ((pointer
    :initarg :pointer
    :initform (cffi:null-pointer)
    :reader pointer))
  (:actual-type :pointer))

(defmacro define-foreign-pointer-wrapper (name)
  `(progn
     (cffi:define-foreign-type ,name (pointer-wrapper)
       ()
       (:simple-parser ,name))

     (defmethod cffi:translate-to-foreign (value (type ,name))
       (check-type value ,name)
       (pointer value))

     (defmethod cffi:translate-from-foreign (value (type ,name))
       (make-instance ',name :pointer value))))

(define-foreign-pointer-wrapper ensure-foo)
(define-foreign-pointer-wrapper ensure-bar)

(cffi:convert-to-foreign (make-instance 'ensure-bar ) 'ensure-foo) ;check-type error \o/
(cffi:convert-to-foreign (make-instance 'ensure-bar ) 'ensure-bar)
(cffi:convert-from-foreign #.(SB-SYS:INT-SAP #X00000123) 'ensure-foo)
(cffi:convert-from-foreign #.(SB-SYS:INT-SAP #X00000456) 'ensure-bar)