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Type test on class member
f#

Hello,

Code in italic is FCL code and can`t be modified.
Is it possible to avoid highlighted type cast?

type Base() = do ()

type A() =
inherit Base()
member x.One = "One"

type B() =
inherit Base()
member x.Two = "Two"

type T (b) =
member x.Base:Base = b

let f (v:obj) =
match v with
| :? T as tt when (tt.Base :? A) ->(tt.Base :?> A).One
| :? T as tt when (tt.Base :? B) ->(tt.Base :?> B).Two
| _ -> "Generic"

.

Looks like an additional dispatch is necessary:

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let f (v:obj) =
    match v with
    | :? T as t ->
        match t.Base with
        | :? A as a -> a.One
        | :? B as b -> b.Two
        | _ -> "Generic"
    | _ -> "Generic"
By on 4/30/2014 6:27 AM ()

Yes, I can't really see a more concise way to do it.

By on 5/1/2014 6:39 AM ()

Duplication of generic branch prone to errors once you need to change generic response. I thought of inner match already, but it doesn't look as concise as I used in F# :)

By on 5/4/2014 12:54 AM ()

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