"David"
"Whatever"
"Name: David"
"Last Name: Whatever"

@dynamicMemberLookup
struct Container<T> {
    let value: T

    subscript<U>(dynamicMember keyPath: KeyPath<T, U>) -> U {
        value[keyPath: keyPath]
    }

    subscript(dynamicMember key: String) -> String {
        "Whatever"
    }
}

struct Person {
    let name: String
}

extension Container where T == Person {
    var containedName: String {
        "Name: \(name)"
    }
}

extension Container {
    var containedLastName: String {
        "Last Name: \(lastName)"
    }
}

let containedPerson = Container(value: Person(name: "David"))
print(containedPerson.name)
print(containedPerson.lastName)
print(containedPerson.containedName)
print(containedPerson.containedLastName)