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https://github.com/wvwwvwwv/async-trait-fn
A fork of async-trait with some useful options
https://github.com/wvwwvwwv/async-trait-fn
async
Last synced: about 2 months ago
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A fork of async-trait with some useful options
- Host: GitHub
- URL: https://github.com/wvwwvwwv/async-trait-fn
- Owner: wvwwvwwv
- License: apache-2.0
- Archived: true
- Fork: true (dtolnay/async-trait)
- Created: 2022-02-23T03:20:52.000Z (over 2 years ago)
- Default Branch: master
- Last Pushed: 2024-03-23T15:05:10.000Z (6 months ago)
- Last Synced: 2024-04-23T16:42:57.317Z (5 months ago)
- Topics: async
- Language: Rust
- Homepage:
- Size: 859 KB
- Stars: 9
- Watchers: 2
- Forks: 1
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE-APACHE
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README
# THE REPOSITORY/CRATE IS NO LONGER MAINTAINED
* Use the `async_fn_in_trait` feature (Rust 1.75.0) or `async_trait`.
# async-trait-fn
[](https://crates.io/crates/async-trait-fn)
This is a fork of the widely acclaimed [async-trait](https://github.com/dtolnay/async-trait) crate. This crate adds two experimental attributes to [async-trait](https://github.com/dtolnay/async-trait) that can be applied to asynchronous trait methods and associated functions to avoid heap memory allocation.
* The return type of an asynchronous trait method or associated function with the `unboxed` or `unboxed_simple` attribute is of `impl Future<..>` instead of `Box>`.
* *Those attributes have a lot of limitations when used in a large software product due to known bugs in Rust generic associated types: e.g., [95719](https://github.com/rust-lang/rust/issues/95719) and [90696](https://github.com/rust-lang/rust/issues/90696).*
Note that, _the main author of [async-trait](https://github.com/dtolnay/async-trait) [did not want to add such options](https://github.com/dtolnay/async-trait/pull/189), therefore this fork will not be merged into the upstream._
See [async-trait](https://github.com/dtolnay/async-trait) for more details about [async-trait](https://github.com/dtolnay/async-trait).
## Examples
`unboxed` turns an asynchronous trait method or associated function into a synchronous one returning an `impl Future<..>` by adding a generic associated type for the method or associated function.
```rust
use async_trait_fn::{async_trait, unboxed_simple};
#[async_trait]
pub trait SelfToUsize {
#[unboxed]
async fn get(&self) -> usize;
}
#[async_trait]
impl SelfToUsize for u32 {
#[unboxed]
async fn get(&self) -> usize {
*self as usize
}
}
```
The compiler generates the following code.
```rust
pub trait SelfToUsize {
fn get<'life0, 'async_trait>(&'life0 self) -> Self::RetTypeOfGet<'life0, 'async_trait>
where
'life0: 'async_trait,
Self: 'async_trait;
type RetTypeOfGet<'life0, 'async_trait>: ::core::future::Future
+ ::core::marker::Send
+ 'async_trait
where
'life0: 'async_trait,
Self: 'async_trait,
Self: 'life0;
}
impl SelfToUsize for u32 {
fn get<'life0, 'async_trait>(&'life0 self) -> Self::RetTypeOfGet<'life0, 'async_trait>
where
'life0: 'async_trait,
Self: 'async_trait,
{
async move {
if let ::core::option::Option::Some(__ret) = ::core::option::Option::None:: {
return __ret;
}
let __self = self;
let __ret: usize = { *__self as usize };
#[allow(unreachable_code)]
__ret
}
}
type RetTypeOfGet<'life0, 'async_trait> = impl ::core::future::Future
+ ::core::marker::Send
+ 'async_trait
where
'life0: 'async_trait,
Self: 'async_trait,
Self: 'life0 ;
}
```
`unboxed_simple` is identical to `unboxed` except that it substitutes all the lifetime bounds and parameters with a single, fixed lifetime: `'async_trait`. When code around an `unboxed` attribute does not compile, `unboxed_simple` _might_ help.
```rust
use async_trait_fn::{async_trait, unboxed_simple};
#[async_trait]
pub trait AddOther {
#[unboxed_simple]
async fn add<'s, 'o>(&'a self, other: &'o usize) -> usize;
}
#[async_trait]
impl AddOther for u32 {
#[unboxed_simple]
async fn add<'s, 'o>(&'a self, other: &'o usize) -> usize {
(*self as usize) + *other
}
}
```
The above code expands to the following code; all the lifetime parameters are replaced with `'async_trait`.
```rust
pub trait AddOther {
fn add<'async_trait>(
&'async_trait self,
other: &'async_trait usize,
) -> Self::RetTypeOfAdd<'async_trait>
where
Self: 'async_trait;
type RetTypeOfAdd<'async_trait>: ::core::future::Future
+ ::core::marker::Send
+ 'async_trait
where
Self: 'async_trait,
Self: 'async_trait;
}
impl AddOther for u32 {
fn add<'async_trait>(
&'async_trait self,
other: &'async_trait usize,
) -> Self::RetTypeOfAdd<'async_trait>
where
Self: 'async_trait,
{
async move {
if let ::core::option::Option::Some(__ret) = ::core::option::Option::None:: {
return __ret;
}
let __self = self;
let other = other;
let __ret: usize = { (*__self as usize) + *other };
#[allow(unreachable_code)]
__ret
}
}
type RetTypeOfAdd<'async_trait> = impl ::core::future::Future
+ ::core::marker::Send
+ 'async_trait
where
Self: 'async_trait,
Self: 'async_trait;
}
```