Example of Binding.of_caller in JRuby

irb.txt

ext-jruby-local ~/projects/jruby $ jruby -X-C -S irb
irb(main):001:0> def foo
irb(main):002:1> a = 1
irb(main):003:1> bar
irb(main):004:1> puts a
irb(main):005:1> end
=> nil
irb(main):006:0> def bar
irb(main):007:1> eval 'a = 2', Binding.of_caller(1)
irb(main):008:1> end
=> nil
irb(main):009:0> foo
2
=> nil

patch.patch

diff --git a/src/org/jruby/RubyBinding.java b/src/org/jruby/RubyBinding.java
index 13ee964..6e5d5a5 100644
--- a/src/org/jruby/RubyBinding.java
+++ b/src/org/jruby/RubyBinding.java
@@ -133,4 +133,10 @@ public class RubyBinding extends RubyObject {
 
         return RubyKernel.eval(context, this, newArgs, Block.NULL_BLOCK);
     }
+    
+    @JRubyMethod(meta = true)
+    public static IRubyObject of_caller(ThreadContext context, IRubyObject self, IRubyObject level) {
+        Binding binding = context.bindingOfCaller((int)level.convertToInteger().getLongValue());
+        return new RubyBinding(context.runtime, (RubyClass)self, binding);
+    }
 }
diff --git a/src/org/jruby/runtime/ThreadContext.java b/src/org/jruby/runtime/ThreadContext.java
index b811b3e..dbe0889 100644
--- a/src/org/jruby/runtime/ThreadContext.java
+++ b/src/org/jruby/runtime/ThreadContext.java
@@ -1276,6 +1276,22 @@ public final class ThreadContext {
     }
 
     /**
+     * Return a binding representing call state from the specified levels above
+     * the current call. This will generally produce unpredictable results when
+     * JRuby's compiler optimizations are active since compiled calls will omit
+     * some or all of this state.
+     * 
+     * @return the binding at the specified level above the current call
+     */
+    public Binding bindingOfCaller(int level) {
+        // FIXME: no bounds check
+        Frame frame = frameStack[frameIndex - level];
+        DynamicScope scope = scopeStack[scopeIndex - level];
+        BacktraceElement element = backtrace[backtraceIndex - level];
+        return new Binding(frame, scope.getStaticScope().getModule(), scope, element.clone());
+    }
+
+    /**
      * Return a binding representing the previous call's state but with a specified self
      * @param self the self object to use
      * @return the current binding, using the specified self