trait Alteration {
    fn method(&self);
}

enum State {
    Foo {var: Box<Alteration>},
    Bar {var: Box<Alteration>}
}

struct Uploader {
    state: State
}

impl Uploader {
    fn problem(&mut self) {
        let next_state = match self.state {
            State::Foo {ref var} => {
                State::Bar {
                    var : *var,
                }
            }
            _ => {
                return;
            }
        };
        self.state = next_state;
    }

}

fn main() {

}