CODEWITHSUNDEEP
crustffiabstract-data-type
Shien
Shien

Reputation: 515

C Abstract Data Type in Rust

I have this code in my header file:

typedef struct _game* Game;

Right now to FFI from Rust I'm doing:

extern "C" {
    pub type Game = usize;
}

Is there a safer way to do this than to treat it like a pointer-sized numeric type? Would this work:

pub struct Game(usize);

Upvotes: 0

Views: 480

Answers (1)

Vladimir Matveev
Vladimir Matveev

Reputation: 127791

You usually model abstract C types in Rust using a pointer to an empty enum:

pub enum _game {}
pub type Game = *mut _game;

This approach explicitly highlights the fact that you cannot create values of _game yourself - you can only get a pointer to it from somewhere.

That said, if you're writing a more high-level wrapper for your library, you should wrap this Game into a more high-level Game, like this:

extern crate your_library_sys;

pub struct Game(your_library_sys::Game);

Here your_library_sys is a "sys" crate which contains low-level FFI bindings to the library. This is a convention which is described in Cargo docs.

Upvotes: 3

Related Questions