test.swift

typealias ContextType = protocol<AComponent, ABComponent>
class Context {
    private let type: ContextType.Type
    init(type: ContextType.Type) { self.type = type }
    var a: A { return type.a }
    var ab: AB { return type.ab }
}
class DebugContext: DefaultAComponent, DefaultABComponent {
    static let a: A = DebugContext.createA()
    static let ab: AB = DebugContext.createAB()
}
class ReleaseContext: DefaultAComponent, SimpleABComponent {
    static let a: A = ReleaseContext.createA()
    static let ab: AB = ReleaseContext.createAB()
}
let debugContext = Context(type: DebugContext.self)
debugContext.ab.getAB()    // => ab
let releaseContext = Context(type: ReleaseContext.self)
releaseContext.ab.getAB()  //=> AB