Re: [racket-dev] FrTime propagation bug
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 On 12-01-12 18:27, Gregory Cooper wrote: Hi Marijn, The value-now/sync procedure waits for propagation to complete before reading a signal's value. Would something like the following suit your purposes? (define a (event-receiver)) (define b (event-receiver)) (define a+b (+ (hold a) (hold b))) (send-event a 3) (send-event b 5) (value-now/sync a+b) ; read a+b after propagation = 8 Or, even simpler: (define c (new-cell)) (define d (new-cell)) (define c+d (+ c d)) (set-cell! c 3) (set-cell! d 5) (value-now/sync c+d) Greg Thanks Greg, that helps a lot, Marijn -BEGIN PGP SIGNATURE- Version: GnuPG v2.0.18 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAk8P8XkACgkQp/VmCx0OL2z0zACeJC+KOeUcuykFuCo8zfUv/nnm RhQAnAvkx7TelLpiQHqSHr26Pu0BC8Ib =KRNI -END PGP SIGNATURE- _ Racket Developers list: http://lists.racket-lang.org/dev
Re: [racket-dev] FrTime propagation bug
Hi Marijn, The value-now/sync procedure waits for propagation to complete before reading a signal's value. Would something like the following suit your purposes? (define a (event-receiver)) (define b (event-receiver)) (define a+b (+ (hold a) (hold b))) (send-event a 3) (send-event b 5) (value-now/sync a+b) ; read a+b after propagation = 8 Or, even simpler: (define c (new-cell)) (define d (new-cell)) (define c+d (+ c d)) (set-cell! c 3) (set-cell! d 5) (value-now/sync c+d) Greg On Thu, Jan 12, 2012 at 12:49 AM, Marijn hk...@gentoo.org wrote: -BEGIN PGP SIGNED MESSAGE- Hash: SHA1 On 11-01-12 21:26, Gregory Cooper wrote: Hi Marijn, FrTime propagates changes asynchronously. When send-event returns, there's no guarantee that the event has finished propagating through the system. And in general, (value-now b) is not well-defined, since asynchronous processing makes it difficult to define what now means; programs should only call this if they can tolerate stale values. Hi Gregory, so just to make sure I understand the implications of this: there is no way to do something like the following: #lang racket (require frtime) (define a (event-receiver)) (define b (event-receiver)) (define a+b (... ??? (merge-e a b))) (send-event a 3) (send-event b 5) (... ??? make sure everything is consistent again) (... ??? get the value 8 out of a+b) Marijn -BEGIN PGP SIGNATURE- Version: GnuPG v2.0.18 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAk8OnpkACgkQp/VmCx0OL2z8tACffv+uhmEAttZ7YhZ4UStbQR6p bFIAn3KOoI5uxWU+5hbWHxxJLgih8l7M =0Y03 -END PGP SIGNATURE- _ Racket Developers list: http://lists.racket-lang.org/dev
[racket-dev] FrTime propagation bug
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 Hi, Consider: #lang racket (require frtime) (define a (event-receiver)) (define b (hold a)) (send-event a 3) ;;; uncomment next line to make it work ;(value-now (hold a)) (value-now b) `a' is an event-stream onto which the value 3 is sent. `b' is the behavior produced by holding the last value seen on `a'. After the value 3 arrives on `a', `b' should hold to 3. But it doesn't unless you ``help'' frtime a bit... Marijn -BEGIN PGP SIGNATURE- Version: GnuPG v2.0.18 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAk8Ns/8ACgkQp/VmCx0OL2yahwCcDFs/1kL+m4PVhfmPdkjTQTcu KmMAnjLaAAHPYvCM1eKkLXl0EBCuXRkE =mrh9 -END PGP SIGNATURE- _ Racket Developers list: http://lists.racket-lang.org/dev
Re: [racket-dev] FrTime propagation bug
Hi Marijn, FrTime propagates changes asynchronously. When send-event returns, there's no guarantee that the event has finished propagating through the system. And in general, (value-now b) is not well-defined, since asynchronous processing makes it difficult to define what now means; programs should only call this if they can tolerate stale values. (It so happens that evaluating (hold a) blocks your thread until the event finishes propagating, but that's an implementation detail. You can probably achieve the same effect through a call to sleep, for example.) Greg On Wed, Jan 11, 2012 at 8:08 AM, Marijn hk...@gentoo.org wrote: -BEGIN PGP SIGNED MESSAGE- Hash: SHA1 Hi, Consider: #lang racket (require frtime) (define a (event-receiver)) (define b (hold a)) (send-event a 3) ;;; uncomment next line to make it work ;(value-now (hold a)) (value-now b) `a' is an event-stream onto which the value 3 is sent. `b' is the behavior produced by holding the last value seen on `a'. After the value 3 arrives on `a', `b' should hold to 3. But it doesn't unless you ``help'' frtime a bit... Marijn -BEGIN PGP SIGNATURE- Version: GnuPG v2.0.18 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAk8Ns/8ACgkQp/VmCx0OL2yahwCcDFs/1kL+m4PVhfmPdkjTQTcu KmMAnjLaAAHPYvCM1eKkLXl0EBCuXRkE =mrh9 -END PGP SIGNATURE- _ Racket Developers list: http://lists.racket-lang.org/dev _ Racket Developers list: http://lists.racket-lang.org/dev
