Trait std::ops::FromResidual
pub trait FromResidual<R = <Self as Try>::Residual> {
fn from_residual(residual: R) -> Self;
}
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
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, E, F> FromResidual<Result<Infallible, E>> for Poll<Option<Result<T, F>>> where
F: From<E>,
© 2010 The Rust Project Developers
Licensed under the Apache License, Version 2.0 or the MIT license, at your option.
https://doc.rust-lang.org/std/ops/trait.FromResidual.html