[swift-evolution] [Proposal] Allow enumerating cases in enumerations

[Karl]

+1

Finally, let’s get it done

> On 4 Jul 2016, at 03:36, Gabriel Lanata via swift-evolution <swift-evolution at swift.org> wrote:
> 
> Hello, this has been proposed multiple times before in different ways. 
> 
> Link to detailed proposal draft:
> https://github.com/gabriellanata/swift-evolution/blob/master/proposals/NNNN-allow-enumerating-cases-in-enumerations.md <https://github.com/gabriellanata/swift-evolution/blob/master/proposals/NNNN-allow-enumerating-cases-in-enumerations.md>
> 
> It is currently not possible to enumerate through all the possible cases of an enumeration object without adding a hardcoded value or recurring to unsafe workarounds. The proposal is to add a method of obtaining an array or set of all the possible cases natively for enumerations without associated values.
> 
> The proposed solution is to implement a native `.cases` static var for all enumerations without associated values. This would provide a strict type-safe way of enumerating though the possible cases without risking runtime errors. The resulting code is a lot cleaner and less prone to errors caused by forgetting to update the hardcoded values when modifying cases.
> 
> Resulting code:
>  
>    enum PokemonType {
>        case Fire, Grass, Water, Wind
>    }
>    for pokemonType in PokemonType.cases {
>        // Do stuff
>    }
>    PokemonType.cases.count // Returns 4
> 
> 
> -------
> Gabriel
> 
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