面向协议的编程 Swift - 可识别

Question

假设我想在 swift 中使用面向协议的编程来模拟幻想游戏。下面的代码产生以下错误：

Protocol 'Character' can only be used as a generic constraint because it has Self or associated type requirements

这里有什么问题？怎么做才对？

protocol Character: Identifiable {
    var name: String {get}
    var maxHealt: Int {get}
    var healt: Int { get set }
}
extension Character {
    var id: String {return name}
    mutating func setHealth(newValue: Int) {
        healt = newValue
    }
}

protocol Fighter {
    var attackPower: Int { get }
}
extension Fighter {
    func attack(enemy: Character ) -> Character {
        var enemy = enemy
        enemy.setHealth(newValue: enemy.maxHealt - self.attackPower)
        return enemy
    }
}

Answer 1

您需要添加通用约束。

extension Fighter {
    func attack<T: Character>(enemy: T ) -> T { //<-- Here
        var enemy = enemy
        enemy.setHealth(newValue: enemy.maxHealt - self.attackPower)
        return enemy
    }
}

面向协议的编程 Swift - 可识别

Protocol oriented Programming Swift - Identifiable

protocols

swift

identifiable