@Override
      public Object writeValue(long value) {
        dt.setTime(DateWritableV2.daysToMillis((int) value));
        ((SettableDateObjectInspector) this.objectInspector).set(obj, dt);
        return obj;
      }
Compiles the appropriate vector expression writers based on a struct object
inspector.
ql/src/java/org/apache/hadoop/hive/ql/exec/vector/expressions/VectorExpressionWriterFactory.java