[swift-evolution] [Proposal] Allow enumerating cases in enumerations
Charlie Monroe
charlie at charliemonroe.net
Tue Jul 5 05:39:56 CDT 2016
Example:
enum MediaKind {
case HomeVideo, Movie, MusicVideo, TVShow
var localizedName: String { ... }
}
let popUpButton: NSPopUpButton = ...
for kind in MediaKind.allKinds {
popUpButton.addItemWithTitle(kind.localizedName)
}
And many, many more.
> On Jul 5, 2016, at 12:33 PM, James Campbell via swift-evolution <swift-evolution at swift.org> wrote:
>
> Would love a real life scenario of why you would need this.
>
> ___________________________________
>
> James⎥Head of Trolls
>
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> Sup
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>
> On 4 July 2016 at 02:36, Gabriel Lanata via swift-evolution <swift-evolution at swift.org <mailto: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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