> That type achieves nothing. The idea of taking params that can't be invalid is that validity is enforced by class invariant. > std::sort doesn't return an i

> That type achieves nothing. The idea of taking params that can't be invalid is that validity is enforced by class invariant. > std::sort doesn't return an instance of Sorted It can't, because it sorts in place and therefore has no control over the sequence. Sorted constructor would sort to guarantee success.