Self-Ref

This crate exposes the macro self_referencing!, which allows the creation of structs in which fields contain references to other fields in the same struct.

This is meant to be a temporary workaround for the problem described here: https://gist.github.com/tomaka/da8c374ce407e27d5dac

This crate will be discontinued if this pattern becomes possible with safe Rust code.

Documentation

Usage

Add to your Cargo.toml:

[dependencies]
self-ref = "0.1"

Use the macro like this:

#![allow(unused_variables)]

#[macro_use]
extern crate self_ref;

struct Galaxy<'a> {
    pub name: &'a str,
}

struct StarSystem<'a> {
    pub galaxy: &'a Galaxy<'a>,
    pub name: &'a str,
}

struct Star<'a> {
    pub system: &'a StarSystem<'a>,
    pub name: &'a str,
}

struct Assets<'a> {
    pub galaxy: Galaxy<'a>,
    pub system: StarSystem<'a>,
    pub star: Star<'a>,
}

fn main() {
    let assets = self_referencing!(Assets, {
        galaxy = Galaxy { name: "Milky Way" };
        system = StarSystem { galaxy: &galaxy, name: "Solar System", };
        star = Star { system: &system, name: "Sol", };
    });
    
    assert_eq!("Milky Way", assets.galaxy.name);
    assert_eq!("Solar System", assets.system.name);
    assert_eq!("Sol", assets.star.name);
    assert_eq!(assets.system.name, assets.star.system.name);
    assert_eq!(assets.galaxy.name, assets.system.galaxy.name);
    assert_eq!(assets.galaxy.name, assets.star.system.galaxy.name);
}

Safety

You must always assign values to all of the struct's fields. If you don't, the others will be uninitialized and can (and most likely will) cause crashes.