This is fair, and what I've done so far in Swift (with a cute little extension on NSLocking no less :). If you're going to add moveonly types with destructors,

This is fair, and what I've done so far in Swift (with a cute little extension on NSLocking no less :). If you're going to add moveonly types with destructors, though, it seems strongly desirable to give them (or at least making available) lexical RAII semantics.