Macro async_clmv_fn_once

macro_rules! async_clmv_fn_once {
    ($($tt:tt)+) => { ... };
}

Async clone move closure that can only be called once.

The macro syntax is exactly the same as async_clmv_fn!, but it does not clone variables again inside the call to move to the returned future. Because it moves the captured variables to the returned Future, the closure can only be FnOnce.

Examples

In the example bar is cloned into the closure and then moved to the future generated by the closure.

async fn foo<F: Future<Output=()>, H: FnOnce(bool) -> F + 'static>(mut f: H) {
    f(true).await;
}

let bar = "Cool!".to_owned();
foo(async_clmv_fn!(bar, |p| {
    std::future::ready(()).await;
    if p { println!("cloned: {bar}") }
}));

println!("original: {bar}");

Expands to:

foo({
    let bar = bar.clone();
    move |p| async move {
        std::future::ready(()).await;
        if p { println!("cloned: {bar}") }
    }
});

Note that this is different from an async once closure, it is an once closure that returns a future, this is so it is more similar with async_clmv_fn!, that macro cannot be implemented an async closure.