Function bin_io::utils::try_cast

pub fn try_cast<R: Read, W: Write, Rf, Wf, I, O>(
    f: (Rf, Wf)
) -> (impl ReadFn<R, I>, impl WriteFn<W, I>) where
    Rf: ReadFn<R, O>,
    Wf: WriteFn<W, O>,
    O: TryFrom<I> + TryInto<I>,
    I: Clone, 

Bidirectional cast.

This is an helper function used in conjuction with seq!.

This is the TryFrom variant of cast.

Reading

The function tries to casts O into I.

Writing

The function tries to casts I into O.

Remarks

Since this cast is bidirectional, each type must be constructible from the other. Therefore remember to implement TryFrom<I> for O and TryFrom<O> for I!

Examples

use std::io::Cursor;
use bin_io::numbers::{ be_u8 };
use bin_io::{ write, try_cast, seq };
 
let vec = Vec::new();
let mut cursor = Cursor::new(vec);
 
struct Unicorn {
    a: usize
}
 
let a = seq!(
    Unicorn { a },
    a: try_cast(be_u8()) =>
);
 
write(&mut cursor, &Unicorn { a: 20 }, a)
    .unwrap();
 
assert_eq!(cursor.get_ref()[0], 20);
 
// Fails to cast!
let err = write(&mut cursor, &Unicorn { a: 256 }, a);
 
assert!(err.is_err());