Does anyone know an efficient way to call instance_eval from C? I'm
currently using 

  rb_funcall(obj, :insteval_proc, 1, my_proc);

with

  def insteval_proc pr
    instance_eval &pr
  end

I've tried various combinations of rb_iterate and rb_obj_instance_eval,
but it always seems to want a string, not a proc. It just seems like
there should be an easy direct way to do this.