WebThe Box is pinned so that the polling methods could be invoked on the value, but also because often it is created out of the desugared future returned by an async fn, which often needs pinning because the data structure produced from the transformed function body has internal references with lifetimes that span across the yield points. WebIf a Future does not implement Unpin, then you need to pin it once and keep it pinned forever. It almost never makes sense to use Box rather than Pin>. Use Box::pin (fut) rather than Box::new (fut). Returning -> impl Future + Unpin from a function is okay-ish, but means that for instance that you can't use async ...

How can one await a result of a boxed future? - Stack Overflow

WebTo use a Future or Stream that isn't Unpin with a function that requires Unpin types, you'll first have to pin the value using either Box::pin (to create a Pin>) or the pin_utils::pin_mut! macro (to create a Pin<&mut T> ). Pin> and Pin<&mut Fut> can both be used as futures, and both implement Unpin. For example: WebMar 24, 2024 · Not all async traits need futures that are dyn Future + Send. To avoid having Send and Sync bounds placed on the async trait methods, invoke the async trait macro as #[async_trait(?Send)] on both the trait and the impl blocks. Elided lifetimes Be aware that async fn syntax does not allow lifetime elision outside of & and &mut references. cdbg public services

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WebTo use a Future or Stream that isn't Unpin with a function that requires Unpin types, you'll first have to pin the value using either Box::pin (to create a Pin>) or the … Webuse http:: {Request, Response, StatusCode}; struct HelloWorld; impl Service>> for HelloWorld { type Response = Response>; type Error = http::Error; type Future = Pin>>>; fn poll_ready(&mut self, cx: &mut Context) -> Poll> { Poll::Ready(Ok( ())) } fn call(&mut self, req: Request>) -> Self::Future { let body: Vec = "hello, world!\n" .as_bytes() … WebMay 3, 2024 · use futures::{future::BoxFuture, FutureExt}; // 0.3.14 fn choose_your_adventure(i: usize) -> BoxFuture<'static, ()> { match i { 0 => async {}.boxed(), … cdbg public facilities projects