struct - Rust 特征状态

Question

我将从 Rust for Rubyist 中的这个怪物“Monster”代码开始:

trait Monster {
    fn attack(&self);
    fn new() -> Self;
}

struct IndustrialRaverMonkey {
    life: int,
    strength: int,
    charisma: int,
    weapon: int,
}

struct DwarvenAngel {
    life: int,
    strength: int,
    charisma: int,
    weapon: int,
} ...
impl Monster for IndustrialRaverMonkey { ...
impl Monster for DwarvenAngel { ...

我担心代码重复。在 Java 中，我将创建定义 attack 方法和基类的接口(interface)，其中包含所有参数(life、strength、charisma, 武器)。我将在 C++ 中使用抽象类做同样的事情。我可以找到一些丑陋和不直观的方法来解决这个问题，但是有减少代码的好方法吗？我的意思是，保持它的可扩展性和可读性。

Answer 1

另一种方法，它有利于组合，并且在需要时更容易从中分离实现(例如，DwarvenAngel 的Characteristics 需要一个额外的字段):

trait Monster {
    fn attack(&self);
}

struct Characteristics {
    life: int,
    strength: int,
    charisma: int,
    weapon: int,
}

struct IndustrialRaverMonkey {
    characteristics: Characteristics
}

struct DwarvenAngel {
    characteristics: Characteristics
}

fn same_attack(c: Characteristics) {
    fail!("not implemented")
}

impl Monster for IndustrialRaverMonkey {
    fn attack(&self) {
        same_attack(self.characteristics)
    }
}

impl Monster for DwarvenAngel {
    fn attack(&self) {
        same_attack(self.characteristics)
    }
}

或者，您可以用一个枚举来表示您的怪物类型，这与 A.B. 的回答非常相似:

trait Monster {
    fn attack(&self);
}

struct Characteristics {
    life: int,
    strength: int,
    charisma: int,
    weapon: int,
}

enum Monsters {
    IndustrialRaverMonkey(Characteristics),
    DwarvenAngel(Characteristics),
}

fn same_attack(_: &Characteristics) {
    fail!("not implemented")
}

impl Monster for Monsters {
    fn attack(&self) {
        match *self {
            IndustrialRaverMonkey(ref c) => same_attack(c),
            DwarvenAngel(ref c)          => same_attack(c)
        }
    }
}