Question

我想要一组不同类型的结构。

Vec不起作用，我认为因为不同的结构是不同的类型，Vec只能包含一种类型。

struct Santa {
    color: String,
    phrase: String,
}
struct Rudolph {
    speed: u32,
    lumens: u32,
}

fn newSanta() -> Santa {
    Santa {
        color: String::from("Red"),
        phrase: String::from("Ho ho ho!"),
    }
}
fn newRudolph() -> Rudolph {
    Rudolph {
        speed: 100,
        lumens: 500,
    }
}

fn main() {
    let santa = newSanta();
    let rudolph = newRudolph();

    let northerners = vec![santa, rudolph]; //fails
}

PS C:\Users\anon> rustc xmas.rs
error[E0308]: mismatched types
  --> xmas.rs:27:32
   |
27 |     let northerners = vec![santa, rudolph]; //fails
   |                                   ^^^^^^^ expected struct `Santa`, found struct `Rudolph`
   |
   = note: expected type `Santa`
              found type `Rudolph`

Answer 1

通常的方法是为每种结构创建一个带有变体的enum。处理它们时，您需要在其枚举变体上match来确定它们的类型。

struct Santa {
    color: String,
    phrase: String,
}
struct Rudolph {
    speed: u32,
    lumens: u32,
}

fn newSanta() -> Santa {
    Santa {
        color: String::from("Red"),
        phrase: String::from("Ho ho ho!"),
    }
}
fn newRudolph() -> Rudolph {
    Rudolph {
        speed: 100,
        lumens: 500,
    }
}

enum Common {
  Santa(Santa),
  Rudolph(Rudolph),
}

fn main() {
    let santa = newSanta();
    let rudolph = newRudolph();

    let northerners = vec![Common::Santa(santa), Common::Rudolph(rudolph)];

    match &northerners[0] {
        Common::Santa(santa) => println!("santa color: {}", santa.color),
        Common::Rudolph(rudolph) => println!("rudolph speed: {}", rudolph.speed),
    }
}

playground

或者，如果他们每个人都实现了一个共同的特征，你可以存储trait objects个特征。

创建不同结构的矢量的常用方法是什么？

1 个答案: