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unboxing obj provided from COM
f#

Hello F# users!

Following the automation examples in the F# source, i created a wrapper for the Bloomberg COM interface (tlbimp.exe). I managed to figure out how to call the appropriate function call but i am having a hard time figuring out how to extract the data into a suitable generic structure for manipulation. Here is a simple example:

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> #r "BLP_DATA_CTRLLib.dll";;                                                                                                                                            

--> Referenced 'm:\research\fs_src\bi\BLP_DATA_CTRLLib.dll'

> open BLP_DATA_CTRLLib ;;                                                                                                                                               

> let blp = new BlpDataClass() ;;                                                                                                                                        

val blp : BlpDataClass

Binding session to 'm:\research\fs_src\bi\BLP_DATA_CTRLLib.dll'...

> blp.BLPSubscribe ;;                                                                                                                                                    

val it : ('a * 'b -> obj) = <fun:it@4>

> let p = blp.BLPSubscribe("IBM US Equity", "PX_LAST") ;;                                                                                                                

val p : obj

>p;;                                                                                                                                                                   

val it : obj = [|[|127.98|]|]

> let price : float array array = (unbox p) ;;                                                                                                                           

val price : float array array

System.InvalidCastException: Unable to cast object of type 'System.Object[,]' to type 'System.Double[][]'.

   at <StartupCode$FSI_0007>.$FSI_0007._main()

stopped due to error

i have tried various forms of unbox, but none seems to do the trick. What am i missing?
thanks for your help.

.

Based on the error message, I think you have an object with type similar to 'o' below.

So code after that may suggest solution.

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#light

let objArr = Array2.create 1 1 (new obj())

objArr.[0,0] <- (12.34 :> obj)

let o = objArr :> obj

printfn "%A" o

let oa : obj[,] = unbox o

let f : float = unbox (oa.[0,0])

printfn "%f" f
By on 8/5/2008 12:23 PM ()

ok, great! that method works. careful analysis of the types is useful...

By on 8/5/2008 7:10 PM ()

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