ruby-rust-interop

Showcasing the calling of number-based functions from Rust in a Ruby runtime

I hope these examples will help you set up Ruby with Rust!

All these examples were tested on Windows with Ruby 2.1.6 and Rust 1.0.0-beta.4

If you clone the repo, make sure you have Ruby and Rust installed on your machine and run

rake

By default, this will compile the src/interop.rs file and run interop.rb to display the result of some number passing.

Ruby's Fiddle library made it super easy, and Yehuda Katz's blog here helped me get set up so thanks for that!

I hope you enjoy the examples, and don't be afraid to ask me any questions.

To Be Going On With

You need 3 ingredients to get this working:

###Step 1

write a function the right way in Rust (read at the bottom for a common problem on Windows and a simple workaround)

#[no_mangle]
pub extern "C" fn fn_name() {}

###Step 2 compile that function the right way

> rustc my_file.rs --crate-type=dylib

###Step 3 use Fiddle to create a method in Ruby from the C code

require 'fiddle'
require 'fiddle/import'

module RustFunctions
  extend Fiddle::Importer
  dlload "./my_file.dll"
  extern "void fn_name()"
end

###Step 4 Now you can use RustFunctions.fn_name anywhere in your ruby code!

Of course, to add parameters and return values, you have to know how to translate between Rust's types and C's types.

#[no_mangle]
pub extern "C" fn fn_name(x: i32) -> i32 {
	println!("You passed in {}", x);
	x + 1
}

Compilation will be the same (you can see why I made a rakefile for that).

And your Fiddle code will require the types:

require 'fiddle'
require 'fiddle/import'

module RustFunctions
  extend Fiddle::Importer
  dlload "./my_file.dll"
  extern "int fn_name(int)"
end

And now, running RustFunctions.fn_name(3) will return 4. Hooray!

Note to Windows users: there is a known compiler bug for compiling dynamic libraries on Windows. At the bottom of that page I share an easy workaround.