具有相关类型的泛型结构实现协议

Question

I am a bit stuck trying to define a container for my ui elements.

As I wanted something that encapsulates a non unique label, a value that can be any comparable object and a concept of being the preferred option I came up with the following protocol:

protocol OptionProtocol:Comparable {
    associatedtype Key:Comparable
    associatedtype Value:Comparable

    var key:Key { get set }
    var value:Value { get set }
    var main:Bool { get set }

    static func <(lhs: Self, rhs: Self) -> Bool

    static func ==(lhs: Self, rhs: Self) -> Bool

}

extension OptionProtocol {
    static func <(lhs: Self, rhs: Self) -> Bool {
        let equalKeys = lhs.key == rhs.key
        return  equalKeys ? lhs.value < rhs.value : lhs.key < rhs.key
    }

    static func ==(lhs: Self, rhs: Self) -> Bool{
        return  (lhs.value == rhs.value) && (lhs.key == rhs.key)
    }
}

Now I want to implement the protocol in a generic struct and I cant figure out how. What I want to do is

struct Option<Key, Value>: OptionProtocol  {
    var key:Key
    var value:Value
    var main:Bool
}

But the compiler complains that Type 'Option<Key, Value>' does not conform to protocol 'OptionProtocol'

Any pointer would be helpful

Answer 1

The answer was pretty simple. I needed to constraint Key and Value in the struct. The following struct compiles as expected

struct Option<Key, Value>:OptionProtocol where Key:Comparable, Value:Comparable {
    var key:Key
    var value:Value
    var main:Bool
}