I'm not sure I follow. When you use unsafe features, you can defeat most any intended invariant; that's what makes them "unsafe", right?
Whether this particular example is ok depends on what you want `unsafe-global` to mean. If you want it to correspond to external state --- such as a filesystem or a remote process --- then it is implemented ok. Otherwise, I agree that the implementation of `unsafe-global` is bad. If you count the behavior as bad, then you're right that fixing it up means using similar unsafe functionality. Specifically, the scheme_register_process_global() function (accessible only via `ffi/unsafe`) helps to implement state that spans instantiations and places. At Tue, 29 Apr 2014 06:10:19 -0600, Jay McCarthy wrote: > If you look at this directory: > > https://github.com/jeapostrophe/exp/tree/master/fffhase-attack > > There's a short "attack" on the promise that different instantiations > of the same module across phases don't share a store. > > Running without compiled version > rm -fr compiled > racket -t phase0.rkt -- > static: unsafe-global was 0 > static: safe-global was 0 > dynamic: unsafe-global is 1 > dynamic: safe-global is 0 > > Running with compiled version > raco make phase0.rkt > racket -t phase0.rkt -- > static: unsafe-global was 0 > static: safe-global was 0 > dynamic: unsafe-global is 0 > dynamic: safe-global is 0 > > Should we consider this fine because the effect is "external" (just > like touching a file) or should there be a generalization of the > racket/gui/base rule that the module can't be instantiated multiple > times? > > A bit of a grep doesn't lead to any easy place where that is > implemented.... it seems like that feature can only be implemented > with a restricted form of the attack itself, so you can observe that > the instantiation already happened. > > Jay > > -- > Jay McCarthy <j...@cs.byu.edu> > Assistant Professor / Brigham Young University > http://faculty.cs.byu.edu/~jay > > "The glory of God is Intelligence" - D&C 93 _________________________ Racket Developers list: http://lists.racket-lang.org/dev
