Ovidiu Predescu wrote: >Sylvain, > >On Wed, 10 Apr 2002 10:14:24 +0200, Sylvain Wallez <[EMAIL PROTECTED]> >wrote: > >>Ovidiu Predescu wrote: >> >><snip/> >> >>>Please do a cvs update and check out the calculator sample again. I've >>>reverted back to using callCC in JavaScript instead of a new API, a >>>Continuation object, provided by Christopher Oliver in his modified >>>Rhino engine. I need to test the later a bit more before using it. >>> >>Ovidiu, can you tell us the status of the work of Christopher Oliver, as >>the continutation-enabled Rhino becomes a critical part of the flow engine : >>- are sources available ? >>- under which licence (same MPL as Rhino) >>- is it/will it be integrated into the main Rhino code base ? >> > >Christopher's work is available in source form from: > >ftp://ftp.primaryinterface.com/pub/rhino/rhino1_5R4pre-callCC.zip >
Cool. >The package also contains a pre-built, ready to use, jar file. The >license is still MPL, and I don't think is possible to change it. > MPL is good. I was wondering if it was something else. >At this point, the primary maintainers of Rhino seem to be concerned >with two things: > >- the performance implications of the continuations code has on the >interpreted engine. > >- the fact that continuations are available in interpreted mode >only. > >Rhino has two ways of running JavaScript scripts. The first one is >translating the script in a structure of internal objects, which are >then "executed". The second approach, a lot faster that the first one, >translates the JavaScript scripts in internal Java classes, which are >compiled to bytecodes on-the-fly and executed as normal Java code. > >Adding support for continuations in the compiler mode is not possible, >due to the impossibility to manipulate the Java stack frame. > >I believe at this point, Norris Boyd and other Rhino maintainers are >waiting for the continuations code to stabilize, and have all the bugs >removed. In the past month Christopher came up with new versions every >other day almost ;-). Some of them had major bugs, and unless somebody >like us tests the code extensively it may be difficult to remove them. > Classical chicken-and-egg problem : people don't want to use something that's not stable, and that thing needs users to stabilize. Let's stabilize it with Cocoon ! >One of the implications for us is that once Schecoon is merged onto >the main trunk, we'll have to use this engine instead of the 1.5R3 >version we currently use. > If the compiled engine is still available in the patched version, then this should be no problem : use interpreted mode for the flow, and compiled mode everywhere else. >I certainly hope Christopher's work will get into the main trunk, so >that we're not stuck with an unsupported version. > >Another alternative, which I still need to explore, is to continue the >development on the language I proposed a while ago. This will give us >much more control over what features we need, and we can possibly have >more optimizations implemented. Rhino is much slower when it comes to >continuations than SISC, the Scheme interpreter I was initially used >in Schecoon. > >And there are certain optimizations which can be done to minimize the >size of the captured continuations, which are simply not possible in >Rhino without major changes. Controlling what gets captured in a >continuation at the language level would also help developers a >lot. For example it would be nice to have language constructs that >tell that a variable's value should not be captured in a continuation, >and how its value could be restored after the continuation is >resurrected. At this point this is just some food for thought, I need >to look more closely into these issues. > That would be an equivalent of the "transient" keyword for local variables. Sylvain -- Sylvain Wallez Anyware Technologies Apache Cocoon http://www.anyware-tech.com mailto:[EMAIL PROTECTED] --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, email: [EMAIL PROTECTED]
