If memory serves: the CLOS Metaobject Protocol had features like this. This 
might be good read if you are considering writing a proposal for this. (Dylan 
Lives! :) )

https://en.wikipedia.org/wiki/The_Art_of_the_Metaobject_Protocol 
<https://en.wikipedia.org/wiki/The_Art_of_the_Metaobject_Protocol>

As I remember, these sorts of features did have scalability issues.


> On Nov 17, 2016, at 3:54 AM, Tino Heth via swift-evolution 
> <[email protected]> wrote:
> 
> An equivalent of "NS_REQUIRES_SUPER" (hopefully with a better name ;-) has 
> been requested several times, but never got the momentum it deserves.
> Considering the current confusion (especially in UIKit), it would be really 
> nice to have some help from the compiler, and I wonder how composition and 
> protocols would be helpful here at all.
> 
> I guess the problem is that there are to many options for this feature 
> without an obvious favorite: Not only for the keywords, but also for the 
> exact semantic.
> 
> Additionally, there are imho already to many access levels (private, 
> fileprivate, internal, public, extendable?, open), so I hope we'll someday 
> find a solution that is powerful enough to replace the special willSet/didSet 
> treatment for properties as well.
> 
> So unless somebody has a real flash of genius, I guess it's better to delay 
> discussion until there is a chance for new proposals to be accepted.
> 
> Tino
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