It does seem useful. It would require some thought because the exception handler cannot escape until there is no possibility of resuming which seems like it would have UI implications. This would also cause some REPL interactions to behave differently when they are in the break-resumable context (notably those involving continuations and related things). But I agree it seems worth thinking about.
Since it's been 7 days and I've not made any more progress than that, I guess that the best I can offer is advice if someone else wants to give it a try. Robby On Mon, Jul 27, 2015 at 5:48 PM, John Carmack <jo...@oculus.com> wrote: > Any chance that could make it in as a DrRacket feature? Seems likely to have > moderately broad utility. > > Out of curiosity, what programming environment do the core Racket devs use > when programming Racket? I quite like DrRacket for my projects that are only > a few files, but it doesn't seem to be aimed at large scale work. > > -----Original Message----- > From: Matthew Flatt [mailto:mfl...@cs.utah.edu] > Sent: Monday, July 27, 2015 2:43 PM > To: John Carmack > Cc: Racket Users > Subject: Re: [racket-users] continuing after a user break > > 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)) > > -- > You received this message because you are subscribed to the Google Groups > "Racket Users" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to racket-users+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/d/optout. -- You received this message because you are subscribed to the Google Groups "Racket Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to racket-users+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
