[plt-scheme] puzzled about multiple value return

GMTA I guess. That was very nice. Thank you both,

-pp



>
> You can use call-with-values, values, and apply:
>
> (define (helper thunk)
>   (setup)
>   (call-with-values thunk
>                     (lambda results
>                       (teardown)
>                       (apply values results))))
>
> Ryan
>
> > Here is my attempt:
> >
> > (define (helper thunk)
> >   (let ((success #t))
> >     (dynamic-wind
> >         (lambda () (printf "Setup~n"))
> >         (lambda ()
> >           (with-handlers (((lambda ex #t)
> >                            (lambda (exn)
> >                              (set! success #f)
> >                              (raise exn))))
> >             (thunk)))
> >         (lambda()
> >           (if success
> >               (printf "Teardown~n"))))))
> >
> > > (helper (lambda () (values 1 2 3)))
> > Setup
> > Teardown
> > 1
> > 2
> > 3
> >
> > > (helper (lambda () 1))a
> > Setup
> > Teardown
> > 1
> >
> > > (helper (lambda () (error "Abort") (values 1 2 3)))
> > Setup
> > > Abort
> >
> > This seems to work, but its ugly. Is there a nicer solution?
> >
> > -pp
> >
> >
> >
> >
> > -pp
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> >
>
>
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