"Actors are reference types, but why classes?"

[Douglas_Gregor]

@michelf

My point was that the too general definition of actor as ‘a class that protects its data from races’ actually isn’t fit for other techniques if it imposes an async requirement. Relying on async is really a specific way to protect from data races.

I feel like you've taken my original statement far too literally. "An actor class is a class that protects its data by serializing access to its stored instance members" is more precise and side-steps all of this.

@michelf

It might be worth having a ‘protected from data races’ flag in the public facing API so you know objects of that class can be safely passed across threads, but it shouldn’t force every call to be awaited on.

This is what @Chris_Lattner3 is specifically addressing with protocol-based actor isolation.

Doug