<div dir="ltr">I think the main missing thing is that the thread you're requiriing the user's program on should be under the control of the custodian. In other words, you'll want to create a new eventspace (under the new custodian) and queue a callback over to it to require the user's program.<div> </div><div>Robby</div></div><div class="gmail_extra"> <div class="gmail_quote">On Thu, Apr 3, 2014 at 4:26 PM, Greg Hendershott <<a href="mailto:greghendershott@gmail.com" target="_blank">greghendershott@gmail.com</a>> wrote: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">So the background for Spencer's question was a problem with my Emacs racket-mode when using racket/gui/base. There's a long-ish bug report comment thread. If you want to read it, at all, you might want to skip to the last few comments, here: <a href="https://github.com/greghendershott/racket-mode/issues/26#issuecomment-39494285" target="_blank">https://github.com/greghendershott/racket-mode/issues/26#issuecomment-39494285</a> Or the TL;DR: I probably don't need racket/sandbox at all. I probably just need a new namespace and a custodian -- in order to do a DrRacket-style "reset the REPL to the source file". Matthew and Robby I know you're both incredibly busy, but if either of you had a chance to look at this code, I'd be grateful. Although part of me hopes you'll say "perfect!", the older/wiser part of me hopes you'll point out X Y and Z problems I don't yet realize I have. It's just these 30 lines of code here: <a href="https://github.com/greghendershott/racket-mode/blob/experimental/sandbox.rkt#L30-L66" target="_blank">https://github.com/greghendershott/racket-mode/blob/experimental/sandbox.rkt#L30-L66</a> <div class="HOEnZb"><div class="h5"> On Sun, Mar 23, 2014 at 8:35 PM, Robby Findler <<a href="mailto:robby@eecs.northwestern.edu">robby@eecs.northwestern.edu</a>> wrote: > It is safe, however, to share the racket/gui/base that you get with the one > in the sandbox. > > Robby > > > On Sun, Mar 23, 2014 at 7:25 PM, Matthew Flatt <<a href="mailto:mflatt@cs.utah.edu">mflatt@cs.utah.edu</a>> wrote: >> >> Yes, this is a limitation of `racket/gui/base`. On initialization, the >> library must register in various non-composable ways with an underlying >> GUI toolkit (callbacks, Objective-C classes, Win32 classes, etc.), and >> so `racket/gui/base` cannot be instantiated multiple times. >> >> At Sun, 23 Mar 2014 20:12:43 -0400, Spencer Florence wrote: >> > I'm attempting to launch multiple evaluators which require `racket/gui`, >> > however I get the error: >> > >> > cannot instantiate `racket/gui/base` a second time in the same process >> > >> > Is `racket/gui/base` maintaining some kind of state thats escaping the >> > sandbox? >> > >> > >> > >> > >> > >> > Example of the problem: >> > >> > #lang racket/base >> > (require racket/sandbox) >> > >> > (call-with-trusted-sandbox-configuration >> > (lambda () >> > (define (make) >> > (make-evaluator 'racket/base >> > #:requires '(racket/gui/base))) >> > >> > (make) >> > (make))) >> > ____________________ >> > Racket Users list: >> > <a href="http://lists.racket-lang.org/users" target="_blank">http://lists.racket-lang.org/users</a> >> ____________________ >> Racket Users list: >> <a href="http://lists.racket-lang.org/users" target="_blank">http://lists.racket-lang.org/users</a> > > > > ____________________ > Racket Users list: > <a href="http://lists.racket-lang.org/users" target="_blank">http://lists.racket-lang.org/users</a> > </div></div></blockquote></div> </div>