pin-project

A crate for safe and ergonomic [pin-projection].

Usage

Add this to your Cargo.toml:

[dependencies]
pin-project = "1"

Examples

[#[pinproject]][pinproject] attribute creates projection types covering all the fields of struct or enum.

use std::pin::Pin;
use pinproject::pinproject;
#[pin_project] struct Struct<T, U> {     #[pin]     pinned: T,     unpinned: U, }
impl<T, U> Struct<T, U> {     fn method(self: Pin<&mut Self>) {         let this = self.project();         let _: Pin<&mut T> = this.pinned; // Pinned reference to the field         let _: &mut U = this.unpinned; // Normal reference to the field     } }

[code like this will be generated][struct-default-expanded]

To use #[pin_project] on enums, you need to name the projection type returned from the method.

use std::pin::Pin;
use pinproject::pinproject;
#[pin_project(project = EnumProj)] enum Enum<T, U> {     Pinned(#[pin] T),     Unpinned(U), }
impl<T, U> Enum<T, U> {     fn method(self: Pin<&mut Self>) {         match self.project() {             EnumProj::Pinned(x) => {                 let _: Pin<&mut T> = x;             }             EnumProj::Unpinned(y) => {                 let _: &mut U = y;             }         }     } }

[code like this will be generated][enum-default-expanded]

See [#[pinproject]][pinproject] attribute for more details, and see [examples] directory for more examples and generated code.

Related Projects

[pin-project-lite]: A lightweight version of pin-project written with declarative macros.

[enum-default-expanded]: https://github.com/taiki-e/pin-project/blob/HEAD/examples/enum-default-expanded.rs [examples]: https://github.com/taiki-e/pin-project/blob/HEAD/examples/README.md [pin-project-lite]: https://github.com/taiki-e/pin-project-lite [pin-projection]: https://doc.rust-lang.org/std/pin/index.html#projections-and-structural-pinning [struct-default-expanded]: https://github.com/taiki-e/pin-project/blob/HEAD/examples/struct-default-expanded.rs

[pinproject]: https://docs.rs/pin-project/latest/pinproject/attr.pin_project.html

License

Licensed under either of Apache License, Version 2.0 or MIT license at your option.

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.

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