There have been a couple times where I've wanted something like this: 1) A nil-resettable property without having to resort to making it an IUO. It would be nice to have the setter able to take a T? but the getter return T, and the setter would provide a default value in the event that it receives nil.
2) Once I was writing an API that would keep an array of things in a property, but I also wanted a shorthand version where the user could set it with a single value and have the setter transform that into the array internally. Looking back though, that's not really defensible; it's easy enough for the call site to just add two characters and write "foo.property = [x]", and I probably wouldn't stand by that example today. On Tue, Sep 19, 2017 at 8:16 AM Nevin Brackett-Rozinsky via swift-evolution <[email protected]> wrote: > This may sound rather strange in the abstract, but recently I have > encountered two situations where I would like to have a setter that accepts > a different type than the getter returns. > > In the first, the getter returns Foo and the setter should accept > “@escaping @autoclosure () -> Foo”, so that the expression assigned to the > property is not evaluated until it is needed. (The closure is stored in a > private property, which the getter evaluates then caches the result.) > > In the second, I want a subscript whose getter returns a concrete type (in > my case, subscripting a matrix by row returns an ArraySlice<Element>) while > the setter can accept something more generic (any kind of Collection with > the correct Element type). > > Thoughts? > > Nevin > _______________________________________________ > swift-evolution mailing list > [email protected] > https://lists.swift.org/mailman/listinfo/swift-evolution >
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