Trait HasherDigest

Source

pub trait HasherDigest:
    Digest<OutputSize = Self::OutSize>
    + Write
    + Send
    + Sync {
    type OutSize: ArrayLength<u8, ArrayType = Self::ArrayType>;
    type ArrayType: Copy;
}

Expand description

Convenience trait and blanket impl for downstream trait bounds.

Useful for downstream code that’s generic over [Digest] hasher H.

§Example

Do this:

fn generic_over_hasher<H>()
where
    H: HasherDigest,
{
    let my_data = [1, 2, 3, 4, 5, 6, 7, 8, 9];
    let mt = HasherMerkleTree::<H, usize>::from_elems(None, &my_data).unwrap();
}

Instead of this:

fn generic_over_hasher<H>()
where
    H: Digest + Write + Send + Sync,
    <<H as OutputSizeUser>::OutputSize as ArrayLength<u8>>::ArrayType: Copy,
{
    let my_data = [1, 2, 3, 4, 5, 6, 7, 8, 9];
    let mt = HasherMerkleTree::<H, usize>::from_elems(None, &my_data).unwrap();
}

Note that the complex trait bound for Copy is necessary:

fn generic_over_hasher<H>()
where
    H: Digest + Write + Send + Sync,
{
    let my_data = [1, 2, 3, 4, 5, 6, 7, 8, 9];
    let mt = HasherMerkleTree::<H, usize>::from_elems(None, &my_data).unwrap();
}