public void read(StorableInput dr)
throws java.io.IOException {
rate.setExpression(dr.readString());
rate.setName(dr.readString());
Storable s = dr.readStorable();
if (s instanceof WrappedStock) {
rate.setSource(((WrappedStock) s).stock);
} else {
rate.setSource(((WrappedReservoir) s).reservoir);
}