[plt-scheme] Chaining exception handlers between threads

From: Noel Welsh (noelwelsh at gmail.com)
Date: Wed Feb 27 08:53:51 EST 2008

Ok, I think my confusion arose from two sources:

 - IIRC the parameter current-exception-handler stored the exception
handler in 37x
 - I don't think the docs actually state what an exception handler is, beyond:

   "A handler to catch exceptions can be associated with a
continuation frame though
    a continuation mark (whose key is not directly accessible)."


  I overlooked this so I had a faulty model of how continuation
handlers interacted with threads.


On Wed, Feb 27, 2008 at 1:41 PM, Matthew Flatt <mflatt at cs.utah.edu> wrote:
> At Mon, 25 Feb 2008 21:41:49 +0000, "Noel Welsh" wrote:
>  > Thanks.  Got it working following Robby's suggestion.  Should the
>  > documentation note that the uncaught-exception-handler is a
>  > non-preserved value?  I assume that's what is going on here.
>  No, `uncaught-exception-handler' is a normal parameter.
>  Maybe you have in mind that `with-handlers' and
>  `call-with-exception-handler' set the parameter? They don't. The
>  current exception handler is determined separately from the
>  parameterization --- unless there isn't a handler in the current
>  continuation, in which case `uncaught-exception-handler' is used.
>  Matthew

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