I'm trying to test some code which takes a reader. I've got a function:
fn next_byte<R: Read>(reader: &mut R) -> ... How can I test it on some array of bytes? The docs say that there's a impl<'a> Read for &'a [u8], which would imply this should work:
next_byte(&mut ([0x00u8, 0x00][..])) But compiler disagrees:
the trait `std::io::Read` is not implemented for the type `[u8]` Why? I explicitly said &mut.
Using rust 1.2.0
You are trying to invoke next_byte::<[u8]>, but [u8] does not implement Read. [u8] and &'a [u8] are not the same type! [u8] is an unsized array type and &'a [u8] is a slice.
When you use the Read implementation on a slice, it needs to mutate the slice in order for the next read to resume from the end of the previous read. Therefore, you need to pass a mutable borrow to a slice.
Here's a simple working example:
use std::io::Read; fn next_byte<R: Read>(reader: &mut R) { let mut b = [0]; reader.read(&mut b); println!("{} ", b[0]); } fn main() { let mut v = &[1u8, 2, 3] as &[u8]; next_byte(&mut v); next_byte(&mut v); next_byte(&mut v); } 