Editing Rust (section)

==Without Traits==
This suffers from fixing the Rng to a specific implementation and prevents dependency inversion causing problems with things like testing and forcing any downstream users to be stuck with the choice. No one will have the option of using their quantum hardware random number generator now.

 extern crate rand;
 use rand::StdRng;

 pub struct Context {
    rng: StdRng,
 }
 impl Context {
    pub fn new() -> Context {
        let seed: &[_] = &[1, 2, 3, 4];
        let mut rng = StdRng::from_seed(seed);
    }
    pub fn set_rng(&self, rng: StdRng) {
        self.rng = rng;
    }
 }
 impl SomeTrait for Context {
     //...Blah
     fn some_function(self) {}
 }
 fn use_context(ctx: &Context) {
     //...Blah
 }
 fn main() {
    let mut ctx = Context::new();
    use_context(&ctx)
 }