#impl #traits #closures #proc-macro #smart-pointers #proc-macro-attributes #impl-block

macro bachue-auto_impl

Automatically implement traits for common smart pointers and closures

1 unstable release

0.5.1 Nov 30, 2021

#24 in #impl-block


860 lines

auto_impl Join the chat at https://gitter.im/auto-impl-rs/Lobby CI Crates.io docs

A proc-macro attribute for automatically implementing a trait for references, some common smart pointers and closures.


This library requires Rust 1.37.0 or newer.

Add auto_impl to your Cargo.toml and just use it in your crate:

// In Rust 2015 you still need `extern crate auto_impl;` at your crate root
use auto_impl::auto_impl;

Add an auto_impl attribute to traits you want to automatically implement for wrapper types. Here is a small example:

// This will generate two additional impl blocks: one for `&T` and one
// for `Box<T>` where `T: Foo`.
#[auto_impl(&, Box)]
trait Foo {
    fn foo(&self);

impl Foo for i32 {
    fn foo(&self) {}

fn requires_foo(_: impl Foo) {}

requires_foo(0i32);  // works: through the impl we defined above
requires_foo(&0i32); // works: through the generated impl
requires_foo(Box::new(0i32)); // works: through the generated impl

For more explanations, please see the documentation and for more examples, see the examples folder.


Licensed under either of

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.


~36K SLoC