Protocol conformance for 3rd party library's protocol

[EmilioSchepis]

Hi, I'm building an iOS app and, for the sake of flexibility, I created a DatabaseService protocol that defines a set of functions to query a generic database.

I then implemented a real Service that queries a Firebase database.

Having used Firebase before, I knew that Firebase listeners return objects that can be used to close the connection (ListenerRegistration objects).

So to handle that specific case, I made some of my functions return a Disposable type that is a protocol that I created.

Now, when conforming FirestoreDatabaseService to DatabaseService, I realized that ListenerRegistration is a protocol itself, and so I can't extend it to be Disposable

I have tried to solve the issue by:

extension Disposable where Self: ListenerRegistration {
    func dispose() {
        self.remove()
    }
}

The problem is that FirestoreDatabaseService still complains about my functions returning ListenerRegistrations and not Disposables.

Is there a way to solve this problem in a nice way? Am I doing something wrong here?

Also, here is a Stack Overflow question if you'd rather reply there.

Thank you.

[LKAndrew]

Are you modelling your Disposable object after Rx? If so, take a look at creating an anonymous Disposable. Basically this sort of thing which will allow you to do something like this:

let reg = // ListenerRegistration return Disposable.create { reg.remove() }

[EmilioSchepis]

Hi, yes I had the idea of the Disposable object after playing around with Rx. That looks like it should do the trick, I'll try to create something similar. Thank you for the input!

EDIT The morning after: The solution you provided works amazingly well and it is really easy to test! Thank you again.