Trait core::ops::FromResidual
source · 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)Expand description
用于指定哪些残差可以转换为哪些 crate::ops::Try
类型。
每个 Try
类型都需要从它自己关联的 Residual
类型重新创建,但也可以有额外的 FromResidual
实现来支持与其他 Try
类型的相互转换。
Required Methods§
sourcefn from_residual(residual: R) -> Self
fn from_residual(residual: R) -> Self
🔬This is a nightly-only experimental API. (
try_trait_v2
#84277)从兼容的 Residual
类型构造类型。
这应该与 branch
方法一致地实现,以便应用 ?
运算符将返回等效的残差: FromResidual::from_residual(r).branch() --> ControlFlow::Break(r)
。
(当涉及相互转换时,它不能是相同的残差。)
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),
);
Run