Collections of Protocol Types - 面向协议的编程

Question

我想要一个协议类型的集合：在这种情况下，我想要一个变量“party”是一个 GameCharacter 类型的数组，这样我就可以把所有符合GameCharacter 里面。

下面的代码会产生以下错误：

Protocol 'GameCharacter' 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 GameCharacter: Identifiable {
    var name: String {get}
    var maxHealt: Int {get}
    var healt: Int { get set }

    }

struct Warrior: GameCharacter, Fighter {
    var name: String
    var maxHealt: Int
    var healt: Int
    var armor: Armor
    var weapon: Weapon
    var resistence: Int
    var id: String {
        return name
    }
}

var party: [GameCharacter] <--- error

Answer 1

在这种情况下，您不应该从 Identifiable（具有泛型）继承您的协议，而是显式添加 id 然后下面（简化）是可编译的

protocol GameCharacter {
    var id: String { get }     // << here !!
    var name: String {get}
    var maxHealt: Int {get}
    var healt: Int { get set }
    
}

struct Warrior: GameCharacter {
    var name: String
    var maxHealt: Int
    var healt: Int
    var resistence: Int
    var id: String {        // << here !!
        return name
    }
}

Answer 2

我相信Identifiable是一个关联类型的协议。不幸的是，Swift 不支持您想要实现的目标，还。

有关此主题的讨论，请参阅 Swift associated types and protocol inheritance and How to use generic protocol as a variable type。这些链接也讨论了可能的解决方案。

Collections of Protocol Types - 面向协议的编程

Collections of Protocol Types - protocol oriented programming

collections

protocols

swift

identifiable