Unable to make a protocol for enum

Question

I am not very good with protocols, and I'm quite stuck right now. I am trying to make a protocol for an enum, which has a name property (or function if it needs to be).

This will allow me to get the name of an enum value, similar to conforming to String alone, but with the first letter capitalised instead. For example, what I want to happen:

enum Furniture: Named {
    case table, chair, lamp
}

Furniture.table.name   // Returns 'Table'
Furniture.chair.name   // Returns 'Chair'
Furniture.lamp.name    // Returns 'Lamp'

Here is what I have so far:

protocol Named {
    var name: String { get }
}

extension Named where Named: String {
    var name: String {
        let str: String = self.rawValue
        return str.prefix(1).uppercased() + str.dropFirst()
    }
}

This gives me errors, and when I try to correct them, another error pops up.

Right now, this shows me the following errors:

Type 'Named' constrained to non-protocol, non-class type 'String'

Value of type 'Self' has no member 'rawValue'

How can I fix this?

Answer 1

Enums get their raw value via the RawRepresentable protocol, so that's what you should use when constraining your extension:

extension Named where Self: RawRepresentable, RawValue == String {
    var name: String {
        let str: String = self.rawValue
        return str.prefix(1).uppercased() + str.dropFirst()
    }
}

You also need to declare that your enum uses a String as the type of its rawValue:

enum Furniture: String, Named {
    case table, chair, lamp
}