pub trait Try {
type Ok;
type Error;
fn into_result(self) -> Result<Self::Ok, Self::Error>;
fn from_error(v: Self::Error) -> Self;
fn from_ok(v: Self::Ok) -> Self;
}
A trait for customizing the behavior of the ? operator.
A type implementing Try is one that has a canonical way to view it in terms of a success/failure dichotomy. This trait allows both extracting those success or failure values from an existing instance and creating a new instance from a success or failure value.
type OkThe type of this value when viewed as successful.
type ErrorThe type of this value when viewed as failed.
fn into_result(self) -> Result<Self::Ok, Self::Error>Applies the "?" operator. A return of Ok(t) means that the execution should continue normally, and the result of ? is the value t. A return of Err(e) means that execution should branch to the innermost enclosing catch, or return from the function.
If an Err(e) result is returned, the value e will be "wrapped" in the return type of the enclosing scope (which must itself implement Try). Specifically, the value X::from_error(From::from(e)) is returned, where X is the return type of the enclosing function.
fn from_error(v: Self::Error) -> SelfWrap an error value to construct the composite result. For example, Result::Err(x) and Result::from_error(x) are equivalent.
fn from_ok(v: Self::Ok) -> SelfWrap an OK value to construct the composite result. For example, Result::Ok(x) and Result::from_ok(x) are equivalent.
impl<T> Try for Option<T> type Ok = T; type Error = NoneError;
impl<T, E> Try for Result<T, E> type Ok = T; type Error = 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.Try.html