Trait wagon_utils::ResultNext

pub trait ResultNext<T, E>: Iterator<Item = Result<T, E>> {
    // Required method
    fn next_result(&mut self) -> Result<T, E>;
}

Quickly get a result from an iterator of Results.

This trait is automatically implemented for any iterator of Results that has an error type that implements From<UnexpectedEnd>.

Required Methods

fn next_result(&mut self) -> Result<T, E>

If you have an iterator that holds Result items, you start having to deal with nested Some(Ok(...)) patterns, which gets annoying quickly. This trait is intended so that the iterator always returns some sort of Result, which can then be unwrapped as needed (probably using ?).

Example

struct IterVec<T, E>(Vec<Result<T, E>>);
#[derive(Debug, Eq, PartialEq)]
enum IterErr {
     SomeErr,
     EndErr
}
impl From<UnexpectedEnd> for IterErr {
}
impl<T, E> Iterator for IterVec<T, E> {
}
 
let mut iter: IterVec<i32, IterErr> = IterVec(vec![Ok(1)]);
assert_eq!(Ok(1), iter.next_result());
assert_eq!(Err(IterErr::EndErr), iter.next_result());

Errors

Should return Err if the underlying item is an Err, or there are no more items in the iterator.

Implementors

impl<T, E: From<UnexpectedEnd>, U: Iterator<Item = Result<T, E>>> ResultNext<T, E> for U