[Jscheme-devel] Patch to allow multiple independent JScheme instances

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

After some delay, here is the promised patch that allows one JVM to host
multiple JScheme instances that are isolated (or not if you want) from
each other.  I can provide the entire changed files on request.

Note that there are two new files: src/jsint/Evaluator.java and
src/jscheme/SchemeEvaluator.java and one removed file:
src/jsint/SI.java.

The two main changes are:

1) jscheme.JS now has to be instantiated rather than just having static
methods.

2) jsint.Scheme has been gutted and now delegates to a thread-local
instance of the new class jsint.Evaluator, which contains almost all of
the code from jsint.Scheme in non-static form.

The way it works is that each JS instance has an instance of Evaluator,
which holds the global variables essentially.  Whenever you invoke a
method on JS, it tells jsint.Scheme to use its Evaluator as the
thread-local Evaluator and any jsint code that calls static methods on
jsint.Scheme gets redirected to that Evaluator.

For most users of JScheme the changes boil down to:

JS js = new JS();
js.eval("(define (f x) (* x x))");

rather than:

JS.eval("(define (f x) (* x x))");

Any feedback on these changes is welcome.  If you choose to incorporate
them then my job becomes much easier :-)

Toby.