scala version http://gist.github.com/80274

JRubyScopeTest.scala

import java.util._
import org.jruby._
import org.jruby.javasupport._
import org.jruby.runtime._
import org.jruby.runtime.builtin._
import org.jruby.runtime.callback._

implicit def javaStr2Ruby(s:String)(implicit runtime: Ruby) = 
  RubyString.newUnicodeString(runtime, s)

def callHoge(clazz:RubyClass)(implicit runtime: Ruby) = {
  clazz.allocate.callMethod(runtime.getCurrentContext, "hoge", "a=1")
  clazz.allocate.callMethod(runtime.getCurrentContext, "hoge", "p a")
}

implicit val runtime = JavaEmbedUtils.initialize(new ArrayList[String])

val myClass = runtime.defineClass("MyClass", runtime.getObject, runtime.getObject.getAllocator)
myClass.defineFastMethod("hoge", new Callback() {
  override def execute(self:IRubyObject, args:Array[IRubyObject], block:Block) = {
    val context = self.getRuntime.getCurrentContext
    self.callMethod(context, "eval", args, block)
  }
  override def getArity = Arity.ONE_REQUIRED
})
callHoge(myClass)

runtime.evalScript("class MyClass2; def hoge(expr); eval(expr); end; end")
callHoge(runtime.getClass("MyClass2"))