[swift-evolution] Object declarations

[Riley Avron]

-1. Agreed for all of Jordan's reasons.


Riley

On 11 December 2015 at 14:55, Jordan Rose via swift-evolution <
swift-evolution at swift.org> wrote:

> -1. Enforced singletons lead to code that can't be unit-tested. Local
> types are occasionally convenient and they can't be unit-tested either, but
> spending one extra line to name the thing isn't going to hurt. You also
> can't pick an initializer here (at least not in this version).
>
> IMHO, this just adds "another kind of thing" just to make code shorter,
> and "shorter" is not the right goal for Swift.
>
> Best,
> Jordan
>
>
> On Dec 11, 2015, at 14:07, Marc Knaup via swift-evolution <
> swift-evolution at swift.org> wrote:
>
> 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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>
>
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