Why can't a custom subscript operator be made generic? That is, Swift allows
this inside a class/struct:
func get<T>(key: String) -> T? { … }
but it doesn’t allow
subscript<T>(key: String) -> T? { … } // syntax error at the
“<"
This doesn’t make sense to me, since subscripts are just syntactic sugar; the
subscript operator ought to support whatever a named function can support.
In this case I’m implementing a class that contains a JSON payload, and I want
clients to be able to flexibly access properties of the JSON and assign them to
values, with implicit type-casting, i.e.
var name: String = revision[“name”] // invoke subscript with
T=String
var age: Int = revision[“age”] // invoke subscript with T=Int
(I got this idea from the Tailor library, although it doesn’t use subscripts,
for reasons I now understand.)
—Jens
PS: I’m using Xcode 7.3; I believe that’s Swift 2.2?
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