Trait AsyncResultExt 

pub trait AsyncResultExt<T, E>: Future<Output = Result<T, E>> + Sized {
    // Provided method
    fn with_context<C>(self, ctx: C) -> WithContext<Self, E, C> 
       where C: FnOnce(&E) -> String { ... }
}

Extension trait providing a .with_context() method for futures resolving to Result<T, E>.

This method allows attaching additional context to errors lazily, by supplying a closure that is only executed if the future resolves to an error.

Example

some_async_fn()
    .with_context(|err| format!("Failed due to: {}", err))
    .await;

Provided Methods

fn with_context<C>(self, ctx: C) -> WithContext<Self, E, C>

where C: FnOnce(&E) -> String,

Adds context to an error produced by this future lazily.

The closure ctx is called only if the future resolves to an error, producing a string context to be attached to the error.

Parameters

• ctx: closure to create context string from error reference

Returns

A future that resolves to Result<T, AsyncError<E>>, where errors are wrapped to include context.

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementors

impl<T, E, Fut> AsyncResultExt<T, E> for Fut

where Fut: Future<Output = Result<T, E>> + Sized,