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

Leonardo Pessoa me at lmpessoa.com
Wed Jul 6 10:48:18 CDT 2016

> The review of "SE-0117: Default classes to be non-subclassable publicly" begins now and runs through July 11. The proposal is available here:
>         https://github.com/apple/swift-evolution/blob/master/proposals/0117-non-public-subclassable-by-default.md
>         * What is your evaluation of the proposal?

+1. Being able to control how a class from my libraries are going to
be used by third-parties could enable a better designed API with more
control of how it is intended to be used. I'm just not fond of using
the proposed keywords ('subclassable' and 'overridable') as they feel
more like protocol or attribute names; I'd be more inclined to use the
alternative 'public open' instead, or 'public(open)' as a second

>         * Is the problem being addressed significant enough to warrant a change to Swift?

I'd say it is significant to every language.

>         * Does this proposal fit well with the feel and direction of Swift?


>         * If you have used other languages or libraries with a similar feature, how do you feel that this proposal compares to those?

C# uses the keyword 'virtual' to explicitly mark methods that can be
overriden (not considered in the alternatives but I'm not a big fan of

>         * How much effort did you put into your review? A glance, a quick reading, or an in-depth study?

I've took (a small) part on the thread discussing this proposal but
followed it closely

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