I support the proposal to introduce abstract classes to Swift. I agree with what has been said about inheritance still being an important feature (despite going slightly out off fashion) and this will make it more useful.
I am just wondering if it is really necessary to have the requirement about having to declare a class as abstract if it "contains one or more abstract methods/properties” as suggested in the proposal. Can’t we just consider the class as abstract as soon as there is at least one unimplemented abstract method/property? Furthermore, do we really need the keyword “abstract” as modifier of a class?