[swift-evolution] [swift-evolution-announce] [Review #2] SE-0117: Default classes to be non-subclassable publicly

Garth Snyder garth at garthsnyder.com
Mon Jul 18 14:32:11 CDT 2016

> Nevin/Garth, please remember final and sealed are two different
> concepts: final prevents anyone from subclassing/overriding while
> sealed prevents from subclassing/overriding *outside* the module they
> are declared. Thus final is not the same as sealed.

No, of course it isn’t. I could well be misguided, but I don’t think I’m disoriented. :-)

Ultimately, the question is whether sealed methods offer any additional utility or advantage beyond that of sealed classes plus final. The existence of “final” is certainly relevant, as it already provides some, but not all, of the features of method-level sealing.

I’d still like to see a really solid use case that requires the full semantics of sealing at the method level.


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