[swift-evolution] Proposal - Allow properties in Extensions

[Paul Cantrell]

On Dec 22, 2015, at 10:45 PM, John McCall via swift-evolution <swift-evolution at swift.org> wrote:
> 
> when you stuff a lot of functionality into a single class in most OO languages, there’s no real way to enforce its division into subsystems, because every method has direct access to every property and every other method.  In contrast, in Swift you can divide that class into distinct components with their own interface, state, and invariants, essentially making each component as good as its own type as far as encapsulation goes.

Can you elaborate on this, John? Extensions and protocols in Swift today still don’t solve the problem that shared _private_ class state has to be centralized. Or were you speaking as if this “properties in extensions” proposal were already implemented?

Cheers,

Paul