#future #async #heap-allocation #no-std

no-std stackfuture

StackFuture is a wrapper around futures that stores the wrapped future in space provided by the caller

4 releases (2 breaking)

0.3.0 Nov 17, 2022
0.2.0 Sep 7, 2022
0.1.1 Aug 15, 2022
0.1.0 Aug 10, 2022

#461 in Asynchronous

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588 downloads per month
Used in asynchelp

MIT license

335 lines


crates.io docs.rs

This crate defines a StackFuture wrapper around futures that stores the wrapped future in space provided by the caller. This can be used to emulate dynamic async traits without requiring heap allocation. Below is an example of how use StackFuture:

use stackfuture::*;

trait PseudoAsyncTrait {
    fn do_something(&self) -> StackFuture<'static, (), { 512 }>;

impl PseudoAsyncTrait for i32 {
    fn do_something(&self) -> StackFuture<'static, (), { 512 }> {
        StackFuture::from(async {
            // function body goes here

async fn use_dyn_async_trait(x: &dyn PseudoAsyncTrait) {

async fn call_with_dyn_async_trait() {

This is most useful for cases where async functions in dyn Trait objects are needed but storing them in a Box is not feasible. Such cases include embedded programming where allocation is not available, or in tight inner loops where the performance overhead for allocation is unacceptable. Note that doing this involves tradeoffs. In the case of StackFuture, you must set a compile-time limit on the maximum size of future that will be supported. If you need to support async functions in dyn Trait objects but these constraints do not apply to you, you may be better served by the async-trait crate.


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