DOD Problem

// I'm using specs for ECS.

#[derive(Component, Debug, Clone)]
#[storage(DenseVecStorage)]
pub struct Navigator {
    destination: Destination,
    path: PathState
}

impl Navigator {
    // Is `navigate` the correct thing to write?
    // It borrows itself mutably to assign the destination and path.
    // This will only be called from systems.
    // But the problem is I do not want the destination to be mutated from
    // outside without setting `path` to `PathState::Finding`.
    pub fn navigate(&mut self, destination: Destination) {
        self.destination = destination;
        self.path = PathState::Finding;
    }
    pub fn destination(&self) -> Destination {
        self.destination
    }
    pub fn arrived(&self) -> bool {
        self.path == PathState::Arrived
    }
    // ...
}