rust - 借用“self”问题

Question

我尝试使示例代码尽可能简单

struct Level;

pub struct GameManager<'self>{
    lvl: Level,
    actors: ~[Actor<'self>]
}
struct Actor<'self>{
    lvl: &'self Level
}
impl<'self> GameManager <'self> {
    pub fn new() -> GameManager{
        GameManager {lvl: Level,actors: ~[]}
    }
    fn spawn_actor<'r>(&'r self) -> Actor<'r>{
        Actor{lvl: &'r self.lvl}
    }
}
fn main() {
    let mut gm = GameManager::new();

    let mut actor1 = gm.spawn_actor();

    gm.actors.push(actor1);


}

错误:

/home/maik/source/test.rs:23:4: 23:13 error: cannot borrow `gm.actors` as mutable because it is also borrowed as immutable
/home/maik/source/test.rs:23     gm.actors.push(actor1);
                                 ^~~~~~~~~
/home/maik/source/test.rs:21:21: 21:23 note: second borrow of `gm.actors` occurs here
/home/maik/source/test.rs:21     let mut actor1 = gm.spawn_actor();

如您所见，我希望 GameManager 生成一个 actor。一个 GameManager 作为一个关卡，我希望所有生成的 actor 都能引用 GameManager 的关卡。

有人可以向我解释这个错误吗？我该如何修复它？

Answer 1

这在 Rust 中似乎是不可能的。

但是我找到了一个解决方案来做到这一点，我只需要封装更多一点，比如

struct Level;
pub struct ActorController{
    lvl: Level
}
pub struct GameManager<'self>{
    actors: ~[Actor<'self>],
    actor_controller: ActorController
}
struct Actor<'self>{
    lvl: &'self Level
}
impl ActorController {
    fn spawn_actor<'r>(&'r self) -> Actor<'r>{
        Actor{lvl: &'r self.lvl}
    }
}
impl<'self> GameManager <'self> {
    pub fn new() -> GameManager{
        GameManager {actors: ~[], actor_controller: ActorController{lvl: Level}}
    }
}
fn main() {
    let mut gm = GameManager::new();

    let actor1 = gm.actor_controller.spawn_actor();

    gm.actors.push(actor1);


}