Generating unique IDs for types at compile time

Question

I want to generate a unique id for every type at compile time. Is this possible in Rust?

So far, I have the following code

//Pseudo code
struct Class         


        

Answer 1

std::any::TypeId does something like that:

use std::any::TypeId;

fn main() {
    let type_id = TypeId::of::<isize>();
    println!("{:?}", type_id);
}

outputs:

TypeId { t: 4150853580804116396 }

Answer 2

This sounds like a job for the bitflags! macro:

#[macro_use] extern crate rustc_bitflags;

bitflags!(
    #[derive(Debug)]
    flags ComponentMask: u8 {
        const Render     = 0b00000001,
        const Position   = 0b00000010,
        const Physics    = 0b00000100
    }
);

// the set of components owned by an entity:
let owned_components:  = Render | Position;

// check whether an entity has a certain component:
if owned_components.contains(Physics) { ... }

http://doc.rust-lang.org/rustc_bitflags/macro.bitflags!.html

Answer 3

If you want to manage type ids manually, you can use my unique-type-id crate. It allows you to specify what ids a type has in a special file. It will generate them at compile time. Currently it can be used in this way:

use unique_type_id::UniqueTypeId;
#[derive(UniqueTypeId)]
struct Test1;
#[derive(UniqueTypeId)]
struct Test2;

assert_eq!(Test1::id().0, 1u64);
assert_eq!(Test2::id().0, 2u64);

It can both generate types using incremental number and use the id from a file.