[swift-evolution] Public classes with private superclass

Tino Heth 2th at gmx.de
Tue Jul 5 06:50:37 CDT 2016

Thanks for the link — imho it's really hard to keep an overview of this list…

So, I'll follow the leader ;-) and delay further posts on this topic

>> Not everything can be solved with protocols (stored properties, anyone?)
> Sure, it's not completely painless, but you can declare
> internal protocol MyClassProtocol {
> 	var foo: Bar { get set }
> }
> public class MyClass: MyClassProtocol {
> 	public var foo: Bar
> }
> It's 1 extra line of code. You declare the contract on stored properties by the protocol and just declare them on the class.
… but this single line only covers a single property in a single class, and you have to implement willSet/didSet in every class if you depend on this behavior.
Protocols are nice, and if support for generics is added in the future, a whole set of problems could be covered with those — but imho even protocols are no silver bullet, and there are situations where they are not the right tool.

> IMHO if you need to hide the hierarchy *that* bad, it usually points to a bad design.
I don't believe in fighting developers with obscurity, so for me, it is not about the hiding, but about clarity:
There is no clear way to express that a certain class shouldn't be used outside its library without hiding all subclasses, too (well, you could write documentation… but no one likes documentation ;-)

Best regards,

More information about the swift-evolution mailing list