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[英]How to implement Swift-like enums with associated values in JavaScript?
[英]How should I implement Default Associated Values with Swift Enums?
Swift 問題是有一種方法可以讓枚舉類型具有一個可以具有關聯值的案例。
我有一個 API 可以為我提供可用的過濾器,API 不太可能但有可能添加其他過濾器類型。 因此,如果 API 發送未知的過濾器類型,我希望將該信息與枚舉相關聯。
以下是我對這樣做的不同想法。
我的前兩次嘗試沒有編譯。 我的第三次嘗試只是感覺有點笨拙。
有沒有人有更好的方法來做到這一點? 你認為我不應該使用枚舉來解決這個問題嗎?
typealias APIFilterIdentifier = String
/* Does Not Compile */
enum EnumTestAssociatedValeu: APIFilterIdentifier {
case Unknown(APIFilterIdentifier)
case Everyone = "everyone"
case Team = "myteam"
}
/* Does not compile */
enum EnumTestDefaultAssociatedValues: APIFilterIdentifier {
case Unknown(APIFilterIdentifier)
case Everyone(APIFilterIdentifier = "everyone")
case Team(APIFilterIdentifier = "myteam")
}
/* Compiles but is there a better way? */
enum EnumTestWithCustomInit {
case Unknown(APIFilterIdentifier)
case Everyone
case Team
init(filterIdentifier: APIFilterIdentifier) {
let everyone: APIFilterIdentifier = EnumTestWithCustomInit.everyoneFilterIdentifier
let team: APIFilterIdentifier = EnumTestWithCustomInit.teamFilterIdentifier
switch filterIdentifier {
case everyone:
self = .Everyone
case team:
self = .Team
default:
self = .Unknown(filterIdentifier)
}
}
func asIdentifer() -> APIFilterIdentifier {
switch self {
case .Everyone:
return EnumTestWithCustomInit.everyoneFilterIdentifier
case .Team:
return EnumTestWithCustomInit.teamFilterIdentifier
case .Unknown(let filterIdentifier):
return filterIdentifier
}
}
private static var everyoneFilterIdentifier: APIFilterIdentifier {
return "everyone"
}
private static var teamFilterIdentifier: APIFilterIdentifier {
return "myteam"
}
}
我知道這有點舊,但是這對你想要的東西有用嗎?
typealias FilterIdentifier = String
enum DefaultAPIFilters: FilterIdentifier {
case Everyone = "everyone"
case Team = "team"
}
enum APIFilters {
case Default(DefaultAPIFilters)
case Custom(FilterIdentifier)
}
let everyoneFilter = APIFilters.Default(.Everyone)
let teamFilter = APIFilters.Default(.Team)
let clownFilter = APIFilters.Custom("clowns_only")
擴展內森佩里的回應:
您可以添加一個
var underlyingString: String {
return getUnderlyingString(self)
}
到枚舉。 然后定義
func getUnderlyingString(apiFilter: APIFilters) -> String {
switch apiFilter {
case .Default(let defaultAPIFilter):
return defaultAPIFilter.rawValue
case .Custom(let custom):
return custom
}
}
根據此答案: Swift 中 Enum 的默認值
我建議使用這種方法
public enum Result {
case passed(hint: String)
case failed(message: String)
static let passed: Self = .passed(hint: "")
}
let res: Result = Result.passed
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