4 で実装される気配は今のところないです。 https://github.com/apple/swift/pull/3866 一回頓挫してから気配なし。

Implement SE-0068: Expanding Swift Self to class members and value types by joewillsher · Pull Request #3866 · apple/swift

What's in this pull request? Implementation start on SE-0068. This does not yet implement allowing Self to refer to the dynamic type in non final classes outside of function signatures, just expan...