asynctraitproto

Async trait prototype using the desugarization described in RFC 3185 Static Async Fn in Traits.

It should be faster than async-trait because it doesn't use allocations on every invocation and type erasure.

Benchmark

Requires these feature flags and a nightly compiler: - #![feature(generic_associated_types)] - #![feature(type_alias_impl_trait)]

Example

```rust

![feature(genericassociatedtypes)]

![feature(typealiasimpl_trait)]

use asynctraitproto::asynctraitproto; struct Foo;

[asynctraitproto]

trait Bar { async fn wait(&self); }

[asynctraitproto]

impl Bar for Foo { async fn wait(&self) { sleep(Duration::from_secs(10)).await; } } ```

Send + Sync

The trait definition can include attributes that indicate, that the resulting Future has to be Send and/or Sync. This is important when using the traits with work stealing schedulers like tokio. ```rust

![feature(genericassociatedtypes)]

![feature(typealiasimpl_trait)]

use asynctraitproto::asynctraitproto; struct Foo;

[asynctraitproto]

trait Bar { #[send] async fn wait(&self); }

[asynctraitproto]

impl Bar for Foo { async fn wait(&self) { todo!() } }

// this trait can now be used with tokio::spawn async fn spawn_trait(foo: T) { let handle = tokio::spawn(async move { foo.wait().await; }); handle.await; } ```

On the other hand this will not compile: ```compile_fail

#![feature(genericassociatedtypes)]

#![feature(typealiasimpl_trait)]

use asynctraitproto::asynctraitproto;

struct Foo;

[asynctraitproto]

trait Bar { async fn wait(&self); }

#[asynctraitproto]

impl Bar for Foo {

async fn wait(&self) {

todo!()

}

}

// this trait can not now be used with tokio::spawn async fn spawn_trait(foo: T) { let handle = tokio::spawn(async move { foo.wait().await; }); handle.await; } ```

License: Unlicense