int paramNumber = expr.getChildren().size();
paramEvaluators = new ExprNodeEvaluator[paramNumber];
paramInspectableObjects = new InspectableObject[paramNumber];
for(int i=0; i<paramNumber; i++) {
paramEvaluators[i] = ExprNodeEvaluatorFactory.get(expr.getChildren().get(i));
paramInspectableObjects[i] = new InspectableObject();
}
paramValues = new Object[expr.getChildren().size()];
outputObjectInspector = ObjectInspectorFactory.getStandardPrimitiveObjectInspector(
udfMethod.getReturnType());
}