Re: What's wrong here?

[Bernt Nilsson <bkn@ida.liu.se>]

> Given these two definitions:
>
> (defstruct flugblog
>  (color 'blue)
>  (size 'huge))
>
> (defun foo ()
> ;;
> ;; Returns the color of a newly-constructed, temporary flugblog
> ;;
>  (let ((x (make-flugblog)))
>   (eval '(flugblog-color x))))
>
> CLISP chokes on (foo).  It complains that x has no value.  I've
stepped
> through this problem, and it seems to have something to do with the
call
> to EVAL.  Any clues?

Yes, "x" is not declared special.

Quoting CLtL 2:

"eval form                                       [Function]

The form is evaluated in the current dynamic environment and a null
lexical environment."

- You can eigther use a local or a global special declaration:

Modify foo;

 (let ((x (make-flugblog)))
     (declare (special x))
  (eval '(flugblog-color x))))

Or evaluate "(defvar x)" before running (or compiling) foo.

-- Bernt

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