public static GenericUDAFEvaluator getGenericWindowingEvaluator(String name,
      List<ObjectInspector> argumentOIs, boolean isDistinct,
      boolean isAllColumns, boolean respectNulls) throws SemanticException {
    Registry registry = SessionState.getRegistry();
    GenericUDAFEvaluator evaluator = registry == null ? null :
        registry.getGenericWindowingEvaluator(name, argumentOIs, isDistinct, isAllColumns, respectNulls);
    return evaluator != null ? evaluator :
        system.getGenericWindowingEvaluator(name, argumentOIs, isDistinct, isAllColumns, respectNulls);
  }
Get the GenericUDAF evaluator for the name and argumentClasses.

@param name
         the name of the UDAF
@param argumentOIs
@param isDistinct
@param isAllColumns
@return The UDAF evaluator
ql/src/java/org/apache/hadoop/hive/ql/exec/FunctionRegistry.java