generic.rs

struct Helper<T> {
	field1: T
}

impl<T> Helper<T> {
	fn new (foo: T) -> Helper<T> {
		Helper { field1: foo }
	}
	
	fn add_one<T: Add> (&mut self, value: T) {
		self.field1 += value;
	}
}

fn main () {
	let mut helper: Helper<int> = Helper::new(3);
	
	println!("helper.field value is {}", helper.field1);

	helper.add_one(2);
	
	println!("helper.field value is {}", helper.field1);
}

gistfile1.txt

cremes$ rustc foo.rs 
foo.rs:11:16: 11:19 error: wrong number of type arguments: expected 2 but found 0
foo.rs:11 	fn add_one<T: Add> (&mut self, value: T) {
          	              ^~~
task 'rustc' failed at 'explicit failure', /opt/local/var/macports/build/_opt_mports_dports_lang_rust/rust/work/rust-0.9/src/libsyntax/diagnostic.rs:41
task '<main>' failed at 'explicit failure', /opt/local/var/macports/build/_opt_mports_dports_lang_rust/rust/work/rust-0.9/src/librustc/lib.rs:453