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

Tino Heth 2th at gmx.de
Mon Jul 11 03:42:33 CDT 2016

> The justification for this proposal is all about supporting the people who are working to design library APIs right, and about maintaining consistency with the design philosophy of Swift. To wit: in Swift, where there’s a default choice, it’s the safe one;
I challenge this claim:
Safety is valued, but Swift cares (and should care!) about pragmatism as well… the most obvious example that comes to my mind are arrays, which have no safeguards that stop you from accessing elements that aren't there.

> where there’s a consequential design decision, it’s explicit.
When there is no explicit statement about subclassiblily, it's reasonable to assume that there hasn't been a consequential design decision… but sadly, discussion like this mainly driven by dogmatism, because there is no evidence for either side.

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