[plt-scheme] which continuation marks when raising new exception?

I believe the answer is "it depends". Do you want the stacktrace from
the first place or the second place? If the first, use
(exn-continuation-marks e) and if the second place, use
(current-continuation-marks).

Robby

On 1/28/07, David T. Pierson <dtp at mindstory.com> wrote:
> Hi all,
>
> When raising an exception in response to a lower-level exception (both
> of which are of type exn?), should I call (current-continuation-marks)
> or use the exn-continuation-marks from the lower-level exception?
>
> I see that the latter is done in at least a couple of places in the
> collections source:
>
> collects/web-server/dispatchers/dispatch-servlets.ss
> collects/make/make-unit.ss
>
> But since I am only partially aware of the purpose of continuation
> marks, I'm not sure if those are special cases or represent the standard
> case.
>
> I will add the answer to the cookbook if no one beats me to it.
>
> Here's code in case it isn't clear in what context I am asking this:
>
> (with-handlers
>  ((exn:fail?
>    (lambda (e)
>      (raise (make-exn:fail:high-level
>              (string->immutable-string "blah")
>              (THIS)))))) ; <-- should (THIS) be
>                          ;     (current-continuation-marks)
>                          ;     or (exn-continuation-marks e)?
>   ...)
>
> Thanks.
>
> David
>
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