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

James Froggatt james.froggatt at me.com
Tue Jul 19 06:13:39 CDT 2016

Based on the discussion, I think the real danger of subclassing is unexpected behaviour - in other words, overriding methods. There doesn't seem to be a need to penalise subclasses which just add properties and extra methods based on them.

I'd be in favour of keeping current behaviour for classes, but having to mark methods explicitly as overrideable, virtual, open, or whatever semantics we decide upon. This seems like the safest syntax.

I'd also support a grouping mechanism for marking methods in this way, similar to extensions' current auto-annotation for ‘public’.

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Group: gmane.comp.lang.swift.evolution 
MsgID: <2C9B4C5A-52C2-4E0E-8B9E-6E5444629D85 at apple.com> 

Hello Swift community,

The second review of "SE-0117: Default classes to be non-subclassable publicly" begins now and runs through July 22. The proposal is available here:


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