SE-0295: Codable synthesis for enums with associated values

[ktoso (Konrad 'ktoso' Malawski 🐟🏴‍☠️)]

Great small improvement ideas @beccadax! Love them all.

@beccadax

There is no particular reason to favor labeled values over unlabeled ones, and I don't think you've proposed any fallback behavior that would allow e.g. case dumpToDisk(volume: String) to decode { "dumpToDisk": {} } without an error.

Instead, I would recommend encoding it as a single flat string, not in a keyed container at all:

"dumpToDisk"

I think that's pretty good actually, +1.

If someone wanted to force the "dumpToDisk": {} anyway it's possible without manually en/decoding, by declaring:

case dumpToDisk(Empty)
struct Empty {}

I guess, which is a simple and natural enough workaround if someone needs this.

@beccadax

it can't be used at the top level of a JSON document (which would need an object or array) and it wouldn't be expressed by CodingKeys .

That's actually fine even in toplevel and we fixed this recently ( [5.2] SR-12275: JSONEncoder on Linux can't encode number JSON fragments by ktoso · Pull Request #2840 · apple/swift-corelibs-foundation · GitHub backport PR to 5.2, works fine on 5.3 ):

  3> String(data: JSONEncoder().encode("hello"), encoding: .utf8)
$R1: String? = "\"hello\""

(related thread Allowing top-level fragments in JSONDecoder )