[Jscheme-user] Multiple independent interpreters

[Toby A. <tob...@pe...>]

I'm wanting to use JScheme as a way to script a J2EE application.  I
want to be able to run a scheme program that can send a closure to the
J2EE application and have it executed by an EJB.  The serialization
support I submitted is one part of this.

The next big hurdle is that I don't want the results of executing a
closure in the EJB to taint future executions, and I want to support
multiple threads executing independently.

Because everything is static, the only way that I can see to have
independent interpreters is to play games with class loaders, i.e. to
create a new class loader to load the JScheme classes for each
interpreter instance.  This approach is unsatisfactory to me because I
intend to run in a J2EE environment and messing with class loaders is
explicitly forbidden by the specification.  The performance impact of
creating a class loader and loading the classes also troubles me.

I propose to make all per-interpreter state (e.g. the dynamic
environments, input/output ports) non-static and introduce a per-thread
"current interpreter".  I see two alternative implementation strategies:

1) Introduce a new class, jsint.Interpreter, that is essentially a
de-static-ed version of jsint.Scheme.  Then, replace the contents of
each static method in jsint.Scheme with delegation to the corresponding
method of the current jsint.Interpreter instance.

2) De-static-ify jsint.Scheme and change every static call to
Scheme.<something> to Scheme.currentInterpreter().<something>.

My questions are:

Does anyone see a better or easier way to achieve what I want?

Which of the two proposed options would be preferred?

Toby.

P.S. Yes, I am volunteering to make these changes.