Hi,
I’m trying to implement something like this using Swift 4 after proposal 0142
is implemented:
```
protocol GenericProtocol {
associatedtype Instance
func foo() -> Instance
func bar() -> Instance
// and more...
}
protocol A: GenericProtocol where Instance == String { }
protocol B: GenericProtocol where Instance == Int { }
protocol C: GenericProtocol where Instance == Double { }
// and more…
class Bar {
var a: A // Error: Protocol ‘A' can only be used as a generic constraint
because it has Self or associated type requirements
var b: B // Error: Protocol ‘B' can only be used as a generic constraint
because it has Self or associated type requirements
var c: C // Error: Protocol ‘C' can only be used as a generic constraint
because it has Self or associated type requirements
// and more...
}
```
However, I’m still getting the `Protocol ‘A' can only be used as a generic
constraint because it has Self or associated type requirements` error.
Instead, the only thing I can do right now is to duplicate my code:
(Just in case your are wondering, I need this syntax to simplify some code I’m
working on https://github.com/TintPoint/Overlay/tree/swift-4.0)
```
protocol A {
func foo() -> String
func bar() -> String
// and more...
}
protocol B {
func foo() -> Int
func bar() -> Int
// and more...
}
protocol B {
func foo() -> Double
func bar() -> Double
// and more...
}
// and more...
class Bar {
var a: A // OK
var b: B // OK
var c: C // OK
// and more...
}
```
Am I doing something wrong here? Is it Swift’s current limitation that can be
improved in a future version of Swift? Or it needs a special syntax and a
separate proposal?
Thank you in advance for your help!
Sincerely,
Justin
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