Thanks for taking the time to reproduce it, Alex. I assume you saw nothing wrong with the overall approach I took for the table, outside of your suggestion to use queue-callback.
I had already tried using queue-callback in my actual program, and got no improvement in behavior. I just tried it again with this test program, and was still able to make it fail. I'll go ahead and report it as a bug. I'm also open to suggestions on how I might coax more information out of the system about the failure. I just found the tutorial on contributing to Racket, I'll read through that and see how hard it is to debug the gui library itself. On Sunday, October 14, 2018 at 7:57:23 PM UTC-4, Alex Harsanyi wrote: > I get the same error too if I run your attached program and just click on > the "All" and "None" buttons a few times. The problem seems to be with > doing GUI container operations that take a long time (adding the message% > objects) inside an event callback. To work around this, you can use > queue-callback, that is, replace the code that calls `show-selected-columns` > > (when changed > (show-selected-columns))) > > with > > (when changed > (queue-callback (lambda () (show-selected-columns))) > > I also think it might be worth reporting this as a bug in the GitHub > racket/gui project. > > Regards, > Alex. > > On Monday, October 15, 2018 at 3:50:20 AM UTC+8, Dan Muller wrote: >> >> DrRacket 7, running on Windows 10 version 1803 >> >> I've been working on a GUI program that needs to show a table of data, >> the columns of which change according to checkbox selections. The >> checkboxes are arranged in several groups, each of which has "All" and >> "None" buttons to allow quick checking and clearing of all buttons in that >> group. >> >> If I stress the program a bit by punching checkboxes and buttons more or >> less randomly, it eventually fails. >> I was able to come up with a smaller program that exhibits the same >> behavior. I've attached it to this message. >> >> Running it from the command line with errortrace gives the most >> information. >> >> $ racket -l errortrace -t failure.rkt >> ptr-ref: contract violation >> expected: (and/c cpointer? (not/c (lambda (p) (pointer-equal? p #f)))) >> given: #f >> argument position: 1st >> other arguments...: >> #<ctype:scheme> >> errortrace...: >> C:\Users\danm\Documents\Racket\NMSRecipes\failure.rkt:124:6: (new >> message% (parent column) (label (number->string item))) >> C:\Users\danm\Documents\Racket\NMSRecipes\failure.rkt:123:4: (for >> ((item column-data)) (new message% (parent column) (label (number->string >> ....)))) >> C:\Users\danm\Documents\Racket\NMSRecipes\failure.rkt:130:4: >> (make-column (format "Column ~a" i) (list-ref column-data i)) >> C:\Users\danm\Documents\Racket\NMSRecipes\failure.rkt:129:2: (for ((i >> selected-indexes)) (make-column (format "Column ~a" i) (list-ref >> column-data i))) >> >> Sometimes it can take a while to get the error; it's quite random. >> >> I'm usually running it in DrRacket, but I've also tried it as a >> standalone executable, with the same result. >> >> The DrRacket IDE isn't quite right after this happens, either. The >> program will fail (with the same error) immediately, if I can even restart >> it. Sometimes a separate black window opens, showing a similar error. The >> IDE usually cannot be exited normally. Most of the text editing functions >> still work, though. >> >> Suggestions for workarounds are welcome. I'd be happy to open an issue on >> GitHub, but wanted to first get opinions on whether there's something wrong >> with my code. >> Also, I'm not sure which of the Racket projects it rightly belongs to, >> since the error reporting doesn't usefully refer to anything outside of my >> own code. >> >> >> -- 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 [email protected]. For more options, visit https://groups.google.com/d/optout.
