Subj : Re: How to use Rhino scopes in a multithreaded environment
To   : netscape.public.mozilla.jseng
From : Attila Szegedi
Date : Thu Mar 10 2005 07:06 pm

That's because regardless of you passing "scope" to foo as its scope, it  
will still execute with sharedScope as its scope (and hence won't see  
"out") - this is how static scoping works. If you invoke  
cx.compileString() from a Context that returns true for  
hasFeature(FEATURE_DYNAMIC_SCOPE), then the generated Function objects  
will not ignore the passed scope object - that's how dynamic scoping works  
and that's what you want.

The only way I know of to turn on dynamic scoping is to create a subclass  
of ContextFactory, override its hasFeature() method, and then use  
ContextFactory.initGlobal() to install that custom context factory as  
*the* context factory used by Context.enter() to create contexts.

Attila.


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On 6 Mar 2005 02:37:35 -0800, ant <torntrousers@gmail.com> wrote:

> I'm embedding Rhino in a multithreaded environment and I'm trying to
> understand how scopes work based on the info at
> http://www.mozilla.org/rhino/scopes.html
>
> I'd like to use a scope shared across threads which contains compiled
> function definitions, and for each thread to have its own scope for
> running calls to those functions. I'd also like to be able to add some
> custom objects to the thread specific scope for use by the function
> calls.
>
> The problem is the functions don't seem to find the objects I add to
> the thread specific scope. The following code demonstrates the
> problem:
>
> public class Test {
>
>   public static void main(String[] args) {
>     Context cx = Context.enter();
>     try {
>
>       Scriptable sharedScope = cx.initStandardObjects(null, true);
>
>       String script = "function foo() {out.println(\"in foo\");}";
>       Script compiledScript = cx.compileString(script,"bla",1,null);
>       compiledScript.exec(cx, sharedScope);
>       Function foo = (Function) sharedScope.get("foo", sharedScope);
>
>       Scriptable scope = cx.newObject(sharedScope);
>       scope.setPrototype(sharedScope);
>       scope.setParentScope(null);
>
>       Object wrappedOut = Context.javaToJS(System.out, scope);
>       ScriptableObject.putProperty(scope, "out", wrappedOut);
>
>       foo.call(cx, scope, scope, new Object[] {});
>
>     } finally {
>       Context.exit();
>     }
>   }
> }
>
> Running this fails with: Exception in thread "main"
> org.mozilla.javascript.EcmaError: ReferenceError: "out" is not
> defined. (bla#1)
>
> What am I doing wrong?
>

.