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by steveklabnik 2043 days ago
Some things want an array of a specific size. If you have a function like https://doc.rust-lang.org/stable/std/primitive.u16.html#meth...

  pub const fn from_be_bytes(bytes: [u8; 2]) -> u16
you can't pass it a slice. This would let you pass a vector to this function.

Now, because this wasn't possible previously, it means many things take a slice, and then check that the length is the length they expect, because that ends up being easier for folks. Stuff like this helps it be able to be done properly.

(This specific function is one example that is done in this style, and it's a pain. I have real world code that looks like

  let foo = u16::from_be_bytes([some_slice[0], some_slice[1]]);
This gets even worse with say, u128::from_be_bytes.)
1 comments

TryInto is already implemented for slices in 1.47, so `let foo = u16::from_be_bytes(some_slice.try_into().unwrap());` would work before 1.48.

This trait wasn't implemented for vectors though, so you would have to write `let foo = u16::from_be_bytes(some_vec.to_slice().try_into().unwrap());`.

With new release you can drop `to_slice()` part. Nothing earth-shattering, but makes sense.

> TryInto is already implemented for slices in 1.47, so `let foo = u16::from_be_bytes(some_slice.try_into().unwrap());` would work before 1.48.

Rustdocs say it was 1.36 even? https://doc.rust-lang.org/nightly/std/primitive.array.html#i...

Yeah, by "In 1.47" I mean that as of 1.47 it was already implemented, didn't check since which version.
Ah fun! I missed that. Time to clean up some code...
That doesn't work with non-copyable types.