extension で親子別々の実装にしたい: Playgroundでは行けた( `･ω´･) #CodePiece

CodePiece.swift

protocol SomeProtocol {
    var name: String { get }
}
class A {}
class B: A {}

extension A: SomeProtocol {}
extension SomeProtocol where Self: A {
    var name: String { return "My name is A" }
}
extension SomeProtocol where Self: B {
    var name: String { return "My name is B" }
}
A().name // My name is A
B().name // My name is B