Re: load in environment

[Stephen Compall]

Jon Wilson wrote:
> The second way is to make the desired environment temporarily be the 
> current module:
>
> (define load-env-2 filename env)
>  (let ((real-current-module (current-module)))
>    (set-current-module! env)
>    (load filename)
>    (set-current-module! real-current-module)))
>
> The second way has the advantage of not reinventing the wheel when it 
> comes to the read-eval loop, but looks rather strange.

It is a sensible enough pattern, easily made exit/reentry-safe with 
dynamic-wind in Scheme:

(define (load filename . env-lst)
  (if (null? env-lst)
      ((@ (guile) load) filename)
      (load-env-2 filename (car env-lst))))

(define (load-env-2 filename env)
  (let ((old-cm #f))
    (dynamic-wind
      (lambda ()
        (set! old-cm (current-module))
        (set-current-module! (environment-module env)))
      (lambda () (load filename))
      (lambda ()
        (set-current-module! old-cm)))))

What other Guile state might you want to modify in the dynamic context 
of a load, though?

--
;;; Stephen Compall ** http://scompall.nocandysw.com/blog **
But you know how reluctant paranormal phenomena are to reveal
themselves when skeptics are present. --Robert Sheaffer, SkI 9/2003