# Trait ethcore_util::standard::ops::Carrier [−] [src]

    pub trait Carrier {
        type Success;
        type Error;
        fn from_success(Self::Success) -> Self;
        fn from_error(Self::Error) -> Self;
        fn translate<T>(self) -> T where T: Carrier<Success=Self::Success, Error=Self::Error>;
    }

Unstable (`question_mark_carrier`)

A trait for types which have success and error states and are meant to work with the question mark operator. When the `?` operator is used with a value, whether the value is in the success or error state is determined by calling `translate`.

This trait is very experimental, it will probably be iterated on heavily before it is stabilised. Implementors should expect change. Users of `?` should not rely on any implementations of `Carrier` other than `Result`, i.e., you should not expect `?` to continue to work with `Option`, etc.

## Associated Types

### `type Success`

Unstable (`question_mark_carrier`)

The type of the value when computation succeeds.

### `type Error`

Unstable (`question_mark_carrier`)

The type of the value when computation errors out.

## Required Methods

### `fn from_success(Self::Success) -> Self`

Unstable (`question_mark_carrier`)

Create a `Carrier` from a success value.

### `fn from_error(Self::Error) -> Self`

Unstable (`question_mark_carrier`)

Create a `Carrier` from an error value.

### `fn translate<T>(self) -> T where T: Carrier<Success=Self::Success, Error=Self::Error>`

Unstable (`question_mark_carrier`)

Translate this `Carrier` to another implementation of `Carrier` with the same associated types.

## Implementors

- `impl<U, V> Carrier for Result<U, V>`

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