Create Discriminated Union Case from String

Question

I\'m trying to create DU cases from strings. The only way I can see doing this is by enumerating over the DU cases via Microsoft.FSharp.Reflection.FSharpType.GetUnionC

Answer 1

I found this handy code snippet...

open Microsoft.FSharp.Reflection

let toString (x:'a) = 
    let (case, _ ) = FSharpValue.GetUnionFields(x, typeof<'a>)
    case.Name

let fromString<'a> (s:string) =
    match FSharpType.GetUnionCases typeof<'a> |> Array.filter (fun case -> case.Name = s) with
    |[|case|] -> Some(FSharpValue.MakeUnion(case,[||]) :?> 'a)
    |_ -> None

... which makes it easy to tack on two lines of code to any DU...

type A = X|Y|Z with
    override this.ToString() = FSharpUtils.toString this
    static member fromString s = FSharpUtils.fromString s