Testing enum cases with associated values

Evolution Discussion
12

That’s an interesting proposal. Here’s a link for reference: [swift-evolution] [proposal draft] new syntax to access a given case's payload

The one thing is the proposed syntax doesn’t handle enum cases without payloads. I think that could be handled by an optional Void, so this comment in the original proposal:

Only enum cases with a payload can be used with this syntax (it would make no sens for cases without a payload).

Would be changed to allow for empty payloads turning into Void?. For example:

enum Result {
    case success(Int)
    case failure
}

let r: Result = foo()

let x: Int? = r.success
let y: Void? = r.failure

assert(r.success == Optional(42))
assert(r.failure == nil)

I think it’s a reasonable compromise, though I still think it’s a bit awkward for the common case. Looks like this is being postponed for now, so we’ll have to live with the alternatives.

Andy

···

On Jan 18, 2017, at 12:20 AM, Anton Zhilin <antonyzhilin@gmail.com> wrote:

AFAICS, Andy needs not default implementations of Equatable, but cases-as-optional-properties—this topic has also been discussed on the list.

enum Result {
    case success(Int)
    case failure(String)
}

let r: Result = foo()

let x: Int? = r.success
let y: String? = r.failure

assert(r.success == Optional(42))
assert(r.failure == nil)