Re: PARSE-ERROR

* Marco Antoniotti wrote:


> Does anybody have a quick suggestion about how to come up with a 
> PARSE-ERROR subclass that recorded also the position of the error?

I think it's enough to subclass it, adding a slot or slots which
record the information:

(define-condition stream-parse-error (parse-error)
  ((stream :initarg :stream
           :reader stream-parse-error-stream)
   (position :initarg :position
             :reader stream-parse-error-position)))

Now I forget if it's portable to define an INITIALIZE-INSTANCE method
for this thing which will initialize the position from the stream - I
think you need to do it at condition creation time because the stream
could well be closed by the time you want to extract the position.
I think it's probably not portable to do that, but I'm sure it works
in LW anyway.

--tim