[swift-evolution] [Review] SE-0117: Default classes to be non-subclassable publicly

[Chris Lattner]

> On Jul 5, 2016, at 5:54 PM, Kevin Lundberg via swift-evolution <swift-evolution at swift.org> wrote:
> 
> * What is your evaluation of the proposal?
> 
> -1 as is. I do not want to be constrained by authors of libraries or
> frameworks into interacting with a system in only the ways they forsee.
> By making the default be non-subclassable, if a designer does not put
> thought into all the ways a class can be used then I as a consumer of
> the library am penalized.

Out of curiosity, what is your feeling about “internal” as the default level of access control?  It seems that following your concern to its logical conclusion would lead to a design where all members of a public class would be forced to be public.  After all, the author of a library or framework may not forsee the need to interact with a member that they did not explicitly mark public.

-Chris