[swift-evolution] [Proposal] Enums with stored properties

Erica Sadun erica at ericasadun.com
Sun Oct 9 19:36:22 CDT 2016

I would love to be able to have stored properties in addition to the varying elements. 

Now, I end up creating a secondary struct T and doing case a(T, whatever), b(T, whatever), c(T, whatever), etc. where the same associated structure is every case, *or* I end up putting the enum into a struct which means the guiding semantics are the struct and not the enumeration. Both approaches are ugly. 

-- E

> On Oct 9, 2016, at 6:03 PM, Jay Abbott via swift-evolution <swift-evolution at swift.org> wrote:
> Mateusz,
> To me, "Enumeration defines a type with well defined set of possible values" seems to contradict the idea of having properties that can have different values. What could you do with this special enum - what would the code that uses it look like?
> On Sun, 9 Oct 2016 at 04:56 Robert Widmann via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> wrote:
> I’ve started doing this to try and mimic “Smart Constructors” in Haskell and I think it works quite well.
> struct Format {
>   enum FormatBacking {
>     case SMALL(Int, Int)
>     case MEDIUM(Int, Int)
>     case LARGE(Int, Int)
>   }

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