[swift-evolution] Object declarations

[Marc Knaup]

Hey guys,

I am working on a proposal which touches (and could even partially depend
on) another interesting concept which I think would be a great addition for
Swift.

Object declarations could be a way to declare a class or struct with
exactly one instance. They are perfect for singletons, anonymous subclasses
and to anonymously implement a protocol.

Here some examples how it could look like:

// singleton
object GlobalResource {
    func doSomething() { … }
}

let resource = GlobalResource

// could all be the same
resource.doSomething()
GlobalResource.doSomething()
GlobalResource.Type.doSomething()


// anonymous subclass
class ViewController: UIViewController {

    override func loadView() {
        view = object: UIView {
            // configure view
        }
    }
}


// anonymous protocol implementation
protocol TapHandler {
    func handleTap()
}

view.tapHandler = object: TapHandler {
    func handleTap() {
        // …
    }
}


Kotlin is an example for a a modern language which uses this concept:
https://kotlinlang.org/docs/reference/object-declarations.html


What do you think about such an addition?
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