That option should not be disallowed. Here is a simple example you might want
to build at some point:
protocol ProtocolName {
associatedtype AssociatedType
}
extension ProtocolName where AssociatedType == Int {
struct InnerType {}
}
--
Adrian Zubarev
Sent with Airmail
Am 17. Oktober 2016 um 20:30:58, Karl via swift-evolution
([email protected]) schrieb:
Is your vision that each conforming type would have to provide its own nested
type as specified by the protocol?
Or could the protocol itself define a nested type and anything could use it?
protocol FloatingPoint: … {
enum RoundingRule {
// Do I put an implementation here?
}
}
No, types which are defined inside the protocol are implemented there.
Providing your own types to satisfy a conformance is what associated types are
for.
If you wanted something like that, you could do it with a nested protocol +
associated type:
protocol FloatingPoint {
protocol _RoundingRule { func round(_ : Super) -> Super }
associatedType RoundingRule : _RoundingRule
}
struct Float : FloatingPoint {
enum RoundingRule : _RoundingRule {
func round(_ val: Float) -> Float {
/* switch self, perform rounding… */
}
}
}
That brings up an interesting point, though - we would need a way to refer to
the outer protocol (I used “Super” here).
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