Extending a Protocol where Self: Generic Type in Swift (Requires Arguments In <…>)

Question

I have a class that takes a generic class Collection: (Model is a class) and a protocol (Resource) that some of the s

Answer 1

The problem is Collection is a generic class so every where you declare it, you must attached the specialized type, like Collection. However extension to a protocol can't be specified with a generic type so you end up not being able to supply T to Collection.

In your case though, T is constrained to be of type Model so why not use that in the default protocol implementation:

extension Resource where Self: Collection {
    func fetch() {
        // default implementation
    }
}