Swift Equatable on a protocol

Question

I don\'t think this can be done but I\'ll ask anyway. I have a protocol:

protocol X {}

And a class:

class Y:X {}

Answer 1

Swift 5.1 introduces a new feature into the language called opaque types
Check code below
that still gets back a X, which might be an Y, a Z, or something else that conforms to the X protocol,
but the compiler knows exactly what is being returned

protocol X: Equatable { }
class Y: X {
    var something = 3
    static func == (lhs: Y, rhs: Y) -> Bool {
        return lhs.something == rhs.something
    }
    static func make() -> some X {
        return Y() 
    }
}
class Z: X {
    var something = "5"
    static func == (lhs: Z, rhs: Z) -> Bool {
        return lhs.something == rhs.something
    }
    static func make() -> some X {
        return Z() 
    }
}



let a = Z.make()
let b = Z.make()

a == b