Extension on Array where element is a generic struct in Swift

Question

How would one extend an array of structs that have a generic type? Please see the below code for what I am trying to do.

struct MyStruct<T: MyProtocol> {
   ...
}

extension Array where Element: MyStruct<T> { // Not sure if T is supposed to be on this line.

    func doWork() -> [T] {
        ...
    }
}

Basically, how would I write the extension to have a method return an array of the generic type passed into the struct.

Damiaan Dufaux · Accepted Answer · 2021-07-19 12:55:37Z

9

You will need to create a protocol with an associated type:

protocol MyGenericStructProtocol {
    associatedtype GenericParameter
}

Let your struct adopt the protocol, either directly, or using an extension:

extension MyStruct: MyGenericStructProtocol {
    typealias GenericParameter = T
}

Now you can reference the generic type inside your extension of Array:

extension Array where Element: MyGenericStructProtocol {
    func doWork() -> [Element.GenericParameter] {
        return []
    }
}

Check out a fully working example on this GitHub gist

edited Jul 19, 2021 at 12:55

answered Aug 7, 2017 at 21:51

Damiaan Dufaux

4,8351 gold badge26 silver badges36 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Extension on Array where element is a generic struct in Swift

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related