No elegent way to stream hash given a hash code about rust-multihash HOT 5 OPEN

(because different digest size).

When you derive a Mutlihash via #[derive(Multihash)], all digests should have the same size. So at least that part should work (others may not ;)

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It is a bit confusing as both Hasher and StatefulHasher implement Default, but you are explicit about what you want Rust will give it to you.

let hasher: StatefulHasher = Identity256::default();

hopefully this works for you :)

from rust-multihash.

Hi 🙂

Thank you for the answer, but this is not what I’m looking for.
I need to get a hasher from a hash code I can’t know ahead of time (see my snippet above).
The issue is precisely that we can’t use StatefulHasher except when using a specific algorithm known at compile-time like you mentioned, which kind of defeat the purpose of multihash to some extend :/
The new API is very nice when using digest is acceptable though!

from rust-multihash.

I had a look. I currently see no way of doing it with the current code. The way things currently work, you cannot return a StatefulHasher based on the Code, as the StatefulHashers depend on specific Digests (please correct me if I'm wrong).

I've one idea though. Lots of the code is generated. So perhaps we could generate a companion struct to the Code enum, which implements the StatefulHasher functionality for all the Codes. That struct would that returned by a Code::hasher() call. I'm not sure if that would work, but it might be worth a try.

from rust-multihash.

I had a look. I currently see no way of doing it with the current code. The way things currently work, you cannot return a StatefulHasher based on the Code, as the StatefulHashers depend on specific Digests (please correct me if I'm wrong).

Exact!

I've one idea though. Lots of the code is generated. So perhaps we could generate a companion struct to the Code enum, which implements the StatefulHasher functionality for all the Codes. That struct would that returned by a Code::hasher() call. I'm not sure if that would work, but it might be worth a try.

This would be really helpful!
However, it might not be very straightforward because StatefulHasher has associated types and implementing structs are using different types (because different digest size).

from rust-multihash.