trying to do an instance_eval on any old object from java

gistfile1.java

package spike;

import org.jruby.embed.ScriptingContainer;

public class Spike {
	public static void main(String[] args) {
		ScriptingContainer container = new ScriptingContainer();
		Object someInstance = container.runScriptlet("Object.new");
		container.callMethod(someInstance, "instance_eval", "self", "<eval>", 1);
	}
}

produces this stack trace

java.lang.NullPointerException
	at org.jruby.runtime.ThreadContext.preExecuteUnder(ThreadContext.java:1304)
	at org.jruby.RubyBasicObject.evalUnder(RubyBasicObject.java:1897)
	at org.jruby.RubyBasicObject.specificEval(RubyBasicObject.java:1851)
	at org.jruby.RubyObject.instance_eval(RubyObject.java:1212)
	at org.jruby.RubyObject$i_method_multi$RUBYINVOKER$instance_eval.call(org/jruby/RubyObject$i_method_multi$RUBYINVOKER$instance_eval.gen:65535)
	at org.jruby.internal.runtime.methods.JavaMethod$JavaMethodZeroOrOneOrTwoOrThreeBlock.call(JavaMethod.java:488)
	at org.jruby.internal.runtime.methods.DynamicMethod.call(DynamicMethod.java:178)
	at org.jruby.RubyClass.finvoke(RubyClass.java:665)
	at org.jruby.javasupport.util.RuntimeHelpers.invoke(RuntimeHelpers.java:552)
	at org.jruby.embed.internal.EmbedRubyObjectAdapterImpl.callEachType(EmbedRubyObjectAdapterImpl.java:448)
	at org.jruby.embed.internal.EmbedRubyObjectAdapterImpl.call(EmbedRubyObjectAdapterImpl.java:392)
	at org.jruby.embed.internal.EmbedRubyObjectAdapterImpl.callMethod(EmbedRubyObjectAdapterImpl.java:332)
	at org.jruby.embed.ScriptingContainer.callMethod(ScriptingContainer.java:1325)
	at spike.Spike.main(Spike.java:9)

This seems to come from pushing a scope for sharing local variables. As far as I tested, when sharing variables feature was off, the exception wasn't raised. This is a bug of embedding API. Please file this. Workaround is setting sharing variables off like below:

container.setAttribute(AttributeName.SHARING_VARIABLES, false);
container.callMethod(someInstance, "instance_eval", "self", "", 1);

This attribute can be changed in each runScriptlet/callMethod by setting the value just before those methods.

Thanks for the explanation and workaround. Where should I file it.?

Sorry for not responding this. I fixed this bug in rev. 34aec51. So, you don't need to set the attribute any more.

Thanks for reporting the bug!