3.0 KiB
pin-project
A crate for safe and ergonomic pin-projection.
Usage
Add this to your Cargo.toml:
[dependencies]
pin-project = "1"
Compiler support: requires rustc 1.37+
Examples
#[pin_project] attribute creates projection types
covering all the fields of struct or enum.
use pin_project::pin_project;
use std::pin::Pin;
#[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
To use #[pin_project] on enums, you need to name the projection type
returned from the method.
use pin_project::pin_project;
use std::pin::Pin;
#[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
See documentation 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.
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.