This library provides two implementations of RAII-style deferred execution: one using dynamic allocation (the default) and one that avoids allocation entirely (no_alloc), with a fixed-capacity array of deferred function pointers.

async-safe-defer

Minimal async- and sync-capable defer crate with:

• ✅ async support
• ✅ no unsafe code
• ✅ no_std + alloc compatible
• ✅ optional no_alloc mode
• ✅ zero dependencies

Inspired by defer, but designed for embedded and async contexts.

Usage

Sync

use async_defer::defer;

fn main() {
    defer!(println!("cleanup"));
    println!("work");
}

Async

use async_defer::async_scope;

async_scope!(scope, {
    scope.defer(|| async { println!("async cleanup") });
    println!("async work");
}).await;

No-alloc

use async_defer::no_alloc::AsyncScopeNoAlloc;

fn task() -> Pin<Box<dyn Future<Output = ()> + 'static>> {
    Box::pin(async { println!("no_alloc") })
}

let mut scope = AsyncScopeNoAlloc::<2>::new();
scope.defer(task);
scope.run().await;