Ruwren: Wren bindings for Rust

Here is an attempt at making some Rust Wren bindings in a more Rust style. It acts at times pretty transparently (you do have to deal with the slot / foreign API), but should be

• More typesafe than using the C API directly
• Shouldn't get in the way of quick execution
• Should be relatively simple to get started

Including

Just add:

toml ruwren = "0.3"

to your Cargo.toml.

Main API

Creating a VM

To create a VM, use the VMConfig struct. To create a basic VM that logs it's output to the console, simply call

rust let vm = VMConfig::new().build();

You can run code by using interpret directly:

rust vm.interpret("main", r##"System.print("Cool beans!")"##).unwrap();

Which returns a Ok(()) on successful execution, and Err(e) on failure (see VMError for more details).

You can also call code defined in Wren using a FunctionHandle like so:

rust vm.interpret("main", r##" class GameEngine { static update(delta) { System.print(delta) } } "##).unwrap(); let handle = vm.make_call_handle(FunctionSignature::new_function("update", 1)); vm.execute(|vm| { vm.get_variable("main", "GameEngine", 0); vm.set_slot_double(0, 0.016); }); vm.call_handle(&handle);

or more directly:

rust vm.interpret("main", r##" class GameEngine { static update(delta) { System.print(delta) } } "##).unwrap(); vm.execute(|vm| { vm.get_variable("main", "GameEngine", 0); vm.set_slot_double(0, 0.016); }); vm.call_handle(FunctionSignature::new_function("update", 1));

Embedding Rust code in Wren

Here's a short example of how you can embed your Russt data into Wren:

```rust use ruwren::{Class, VM, VMConfig, ModuleLibrary, getslotchecked, create_module}; struct Foo { bar: f64, }

impl Class for Foo { fn initialize(vm: &VM) -> Self { let bar = getslotchecked!(vm => num 1); Foo { bar } } }

impl Foo { fn instance(&self, vm: &VM) { vm.setslotdouble(0, self.bar); }

fn static_fn(vm: &VM) {
    let num = get_slot_checked!(vm => num 1);
    vm.set_slot_double(0, num + 5.0)
}

}

createmodule! { class("Foo") crate::Foo => foo { instance(fn "instance", 0) instance, static(fn "staticfn", 1) static_fn }

module => foobar

}

fn main() { let mut lib = ModuleLibrary::new(); foobar::publish_module(&mut lib);

let vm = VMConfig::new().library(&lib).build();
vm.interpret("foobar", r##"
foreign class Foo {
    construct new(bar) {}
    foreign instance()
    foreign static static_fn(num)
}
"##).unwrap();

// You could now write Wren code like:

vm.interpret("main", r##"
import "foobar" for Foo
var f = Foo.new(4)
System.print(Foo.static_fn(f.instance()))
"##).unwrap();

// This should print "9".

} ```