Pfthb

When I try use func obj func, I get the error:

Cannot invoke 'obj' with an argument list of type '(message: (QueueAddable))'

I'm confused with Swift types.
Obj func used to get concrete type for decode.

protocol QueueAddable: Encodable 
 var playlistsCollection:String? get 
 var playlists: [String]? get 


struct Playlist: QueueAddable 
 var playlistsCollection:String? 
 return "id"
 
 var playlists: [String]? 
 return ["id", "id2"]
 
 private enum CodingKeys:String,CodingKey 
 case playlistsCollection
 case playlists
 

 public func encode(to encoder: Encoder) throws 
 var values = encoder.container(keyedBy: CodingKeys.self)
 try values.encode(playlistsCollection, forKey: Playlist.CodingKeys.playlistsCollection)
 try values.encode(playlists, forKey: .playlists)
 


func obj<Q>(message: Q) where Q: QueueAddable 
 let encoder = JSONEncoder()
 let data = try! encoder.encode(message)


enum SomeEnum 
 case playlist(QueueAddable)
 func doSome() throws -> Data 
 switch self 
 case .playlist(let queueAddable):
 let encoder = JSONEncoder()

 // Error on the following line:
 obj(message: queueAddable)
 return Data()
 
 


let playlist = Playlist()
let data = try SomeEnum.playlist(playlist).doSome()

I think the problem is that the function expects a type and not a protocol. If you make the enum generic using a type that implements the protocol it will work.

Change the enum's first two lines like this:

enum SomeEnum<Q : QueueAddable> {
case playlist(Q)

I tested in the following playground:

import Foundation

protocol QueueAddable: Encodable 
 var playlistsCollection:String? get 
 var playlists: [String]? get 


struct Playlist: QueueAddable 
 var playlistsCollection:String? 
 return "id"
 
 var playlists: [String]? 
 return ["id", "id2"]
 
 private enum CodingKeys:String,CodingKey 
 case playlistsCollection
 case playlists
 

 public func encode(to encoder: Encoder) throws 
 var values = encoder.container(keyedBy: CodingKeys.self)
 try values.encode(playlistsCollection, forKey: Playlist.CodingKeys.playlistsCollection)
 try values.encode(playlists, forKey: .playlists)
 


func obj<Q>(message: Q) where Q: QueueAddable 
 let encoder = JSONEncoder()
 let data = try! encoder.encode(message)


enum SomeEnum<Q : QueueAddable> 
 case playlist(Q)
 func doSome() throws -> Data 
 switch self 
 case .playlist(let queueAddable):
 let encoder = JSONEncoder()

 // No longer error on the following line:
 obj(message: queueAddable)
 return Data()
 
 


let playlist = Playlist()
let data = try SomeEnum.playlist(playlist).doSome()

Hope it helps!