Docs4dev
Docs
rust / latest / std / ops / trait.fromresidual.html

Trait std::ops::FromResidual

pub trait FromResidual<R = <Self as Try>::Residual> {
    // Required method
    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

source 
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),
);

Object Safety

This trait is not object safe.

Implementors

source 
impl<B, C> FromResidual for ControlFlow<B, C>
source 
impl<T> FromResidual for Option<T>
source 
impl<T> FromResidual<Yeet<()>> for Option<T>
source 
impl<T, E, F> FromResidual<Result<Infallible, E>> for Result<T, F>
where
    F: From<E>,
source 
impl<T, E, F> FromResidual<Result<Infallible, E>> for Poll<Option<Result<T, F>>>
where
    F: From<E>,
source 
impl<T, E, F> FromResidual<Result<Infallible, E>> for Poll<Result<T, F>>
where
    F: From<E>,
source 
impl<T, E, F> FromResidual<Yeet<E>> for 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