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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 问题是有一种方法可以让枚举类型具有一个可以具有关联值的案例。
我有一个 API 可以为我提供可用的过滤器,API 不太可能但有可能添加其他过滤器类型。 因此,如果 API 发送未知的过滤器类型,我希望将该信息与枚举相关联。
以下是我对这样做的不同想法。
我的前两次尝试没有编译。 我的第三次尝试只是感觉有点笨拙。
有没有人有更好的方法来做到这一点? 你认为我不应该使用枚举来解决这个问题吗?
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"
}
}
我知道这有点旧,但是这对你想要的东西有用吗?
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")
扩展内森佩里的回应:
您可以添加一个
var underlyingString: String {
return getUnderlyingString(self)
}
到枚举。 然后定义
func getUnderlyingString(apiFilter: APIFilters) -> String {
switch apiFilter {
case .Default(let defaultAPIFilter):
return defaultAPIFilter.rawValue
case .Custom(let custom):
return custom
}
}
根据此答案: Swift 中 Enum 的默认值
我建议使用这种方法
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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