Rust Function Overloading Macros

This repository is a Rust Foundation experiment in ergonomic function overloading in Rust.

The experiment uses macros to improve the ergonomics of the splat Rust language experiment. Technical details for the current stage of the experiment can be found on the Inside Rust blog.

Most of this code requires a recent nightly Rust compiler.

Macro Setup

Install a recent version of the nightly Rust compiler, and use it to build your project. Add this overloading-macros crate as a dependency.

rustup update nightly
cd your-project-name
rustup override set nightly
cargo add overloading-macros ||  cargo add --git https://github.com/rustfoundation/overloading-macros overloading-macros

Then use the macro to add overloading to your functions or methods.

#![feature(splat, tuple_trait)]
#![allow(incomplete_features, unused_braces)]

use splat_overload::overload;

// Functions can be overloaded
overload! {
    fn show(num: i32) { println!("num: {}", num); }
    fn show(nums: Vec<i32>) { println!("nums: {:?}", nums); }
}

struct Example;

// So can methods and return values
overload! {
    impl Example {
        fn tell(&self, num: i32) -> i32 { println!("num: {}", num); return num; }
        fn tell(&self, nums: Vec<i32>) -> Vec<i32> { println!("nums: {:?}", nums); return nums; }
    }
}

fn main() {
    show(42);
    show(vec![42, 43, 44]);

    let e = Example;
    let _num = e.tell(42);
    let _nums = e.tell(vec![42, 43, 44]);
}

PRs are welcome, particularly to:

• improve the macro's ergonomics
• document how to import overloads into other modules
• fix bugs in this experimental macro

Macro Development Setup

rustup update nightly
git clone https://github.com/rustfoundation/overloading-macros
cd overloading-macros
rustup override set nightly
cargo build

Running Examples

Run individual example binaries with:

cargo run --bin <filename>

For example:

cargo run --bin multiple-args