Trait std::ops::FromResidual

pub trait FromResidual<R = <Self as Try>::Residual> {
    fn from_residual(residual: R) -> Self;
}

🔬 This is a nightly-only experimental API. (try_trait_v2 #84277)

Used to specify which residuals can be converted into which crate::ops::Try types.

Every Try type needs to be recreatable from its own associated Residual type, but can also have additional FromResidual implementations to support interconversion with other Try types.

Required methods

fn from_residual(residual: R) -> Self

🔬 This is a nightly-only experimental API. (try_trait_v2 #84277)

Constructs the type from a compatible Residual type.

This should be implemented consistently with the branch method such that applying the ? operator will get back an equivalent residual: FromResidual::from_residual(r).branch() --> ControlFlow::Break(r). (It must not be an identical residual when interconversion is involved.)

Examples

#![feature(try_trait_v2)]
use std::ops::{ControlFlow, FromResidual};

assert_eq!(Result::<String, i64>::from_residual(Err(3_u8)), Err(3));
assert_eq!(Option::<String>::from_residual(None), None);
assert_eq!(
    ControlFlow::<_, String>::from_residual(ControlFlow::Break(5)),
    ControlFlow::Break(5),
);

Implementors

impl<B, C> FromResidual<<ControlFlow<B, C> as Try>::Residual> for ControlFlow<B, C>

impl<T> FromResidual<<Option<T> as Try>::Residual> for Option<T>

impl<T> FromResidual<<Ready<T> as Try>::Residual> for Ready<T>

impl<T> FromResidual<Ready<Infallible>> for Poll<T>

impl<T, E, F> FromResidual<Result<Infallible, E>> for Result<T, F> where
    F: From<E>, 

impl<T, E, F> FromResidual<Result<Infallible, E>> for Poll<Option<Result<T, F>>> where
    F: From<E>, 

impl<T, E, F> FromResidual<Result<Infallible, E>> for Poll<Result<T, F>> where
    F: From<E>,