At Mon, 27 Jul 2015 19:32:32 +0000, John Carmack wrote:
> Is it possible to continue execution after a ^b user break in DrRacket (not
> debugging)? It would often be useful to be able to ^b, print some global
> state, set some flags, and continue running.
The `exn:break` exception record includes a `continuation` field. An
exception handler can apply that continuation to resume from the point
of the break.
A significant limitation is that the handler has to be installed with
`call-with-continuation-handler` or `uncaught-exception-handler`. If
any `with-handlers` is in effect, it will catch any continuation and
escape to the `with-handlers` form, at which point the continuation in
`exn:break` cannot be applied (because it's an escape-only
continuation).
----------------------------------------
#lang racket
(let ([orig (uncaught-exception-handler)])
(uncaught-exception-handler
(lambda (exn)
(if (exn:break? exn)
(begin
(printf "continuing...\n")
((exn:break-continuation exn)))
(orig exn)))))
(let loop () (loop))
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