2 releases
0.1.1 | Nov 26, 2022 |
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0.1.0 | Nov 26, 2022 |
#84 in #async-trait
Used in fast_async_trait
24KB
537 lines
Fast Async Trait
Library to implement async traits that aren't reliant on boxed futures, relying instead on the type_alias_impl_trait
nightly feature for it's base implementation.
Limitations
- Currently, only one lifetime per async function is allowed
pub trait AsyncTrait {
// allowed
async fn test1 (&self, right: u8);
// allowed
async fn test2 (&self, right: &u8);
// allowed
async fn test3<'b> (&'b self, right: &'b u8);
// compiler error
async fn test4<'b> (&self, right: &'b u8);
}
- Async functions with
Self: Rc<Self>
and similar aren't currently supported
Example
#![feature(type_alias_impl_trait)]
use fast_async_trait::*;
#[async_trait_def]
pub trait AsyncTrait {
type Item;
async fn owned (self) -> Option<Self::Item>;
async fn by_ref (&self) -> Option<Self::Item>;
async fn by_mut (&mut self) -> Option<Self::Item>;
#[inline]
async fn owned_default (self, _n: usize) -> Option<Self::Item> where Self: Sized {
return self.owned().await
}
#[inline]
async fn by_ref_default (&self, n: usize) -> Option<Self::Item> {
for _ in 0..n {
let _ = self.by_ref().await;
}
return self.by_ref().await
}
#[inline]
async fn by_mut_default (&mut self, n: usize) -> Option<Self::Item> {
for _ in 0..n {
let _ = self.by_mut().await;
}
return self.by_mut().await
}
}
#[async_trait_impl]
impl AsyncTrait for (usize, &[u8]) {
type Item = u8;
async fn owned (self) -> Option<Self::Item> {
return self.1.get(self.0).copied()
}
#[inline]
async fn by_ref (&self) -> Option<Self::Item> {
return self.1.get(self.0).copied()
}
#[inline]
async fn by_mut (&mut self) -> Option<Self::Item> {
let v = self.1.get(self.0).copied();
self.0 += 1;
return v;
}
}
Nightly features
The type_alias_impl_trait
nightly feature is required to be able to add impl Trait
types (in our case, impl Future
types) as associated generic types of a trait, which this crate relies on.
Dependencies
~1.5MB
~36K SLoC