我正在尝试用 Rust 编写一个纸牌游戏,但在借用检查器上遇到了一些问题。我的主要struct
是Game
,看起来像这样
struct Game {
players: HashMap<String, Player>,
deck: Vec<Card>,
}
播放器类似于
struct Player {
hand: Vec<Card>,
}
为简单起见,我们可以假设,Card
看起来像
struct Card {
text: String,
}
现在我很自然地想从Game.deck
impl Game {
fn draw_cards(&mut self, num: usize) -> Option<Vec<Card>> {
if self.deck.len() >= num {
let mut cards: Vec<Card> = Vec::new();
for _ in 0..num {
cards.push(self.deck.pop().unwrap());
}
Some(cards)
} else {
None
}
}
}
并将它们附加到玩家的手上
impl Game {
fn draw_to_player(&mut self, name: &String, num: usize) -> Result<(), ()> {
let cards = self.draw_cards(num);
match cards {
Some(mut cards) => {
let player = self.players.get_mut(name);
match player {
Some(player) => {
player.hand.append(&mut cards);
Ok(())
},
None => Err(()),
}
},
None => Err(()),
}
}
到目前为止,一切正常。开始游戏时,我想遍历所有玩家并让他们画起手:
fn draw_for_all(&mut self) {
for name in self.players.keys() {
self.draw_to_player(name, 2);
}
}
这不起作用,因为self
在迭代键时被借用,但必须可变地借用才能调用draw_to_player
:
error[E0502]: cannot borrow `*self` as mutable because `self.players` is also borrowed as immutable
--> src/main.rs:48:13
|
47 | for name in self.players.keys() {
| ------------ immutable borrow occurs here
48 | self.draw_to_player(name, 2);
| ^^^^ mutable borrow occurs here
49 | }
| - immutable borrow ends here
我该如何解决这个问题?