ExcelWorkbook.fs

/// be explicite: path might be None (pseudo overloading)
type ExcelWorkbook(path: string option, fname: string) =
    /// should be a singleton shared by workbooks?
    let excel = getExcel()
    let fqn = 
        match path with 
        | Some path -> path+"\\"+fname 
        | _ -> System.Environment.CurrentDirectory+fname 
    let workbooks = 
        match excel with 
        | Some excel -> getWorkbooks excel 
        | _ -> None
    let workbook = 
        match workbooks with 
        | Some workbooks -> getWorkbook workbooks fqn
        | _ -> None
    let sheets = 
        match workbook with 
        | Some workbook -> Some workbook.Sheets 
        | _ -> None
    /// would want to manage an array of sheet(s) ?
    let mutable sheet = None

    /// Finally destilled from: 
    /// http://stackoverflow.com/questions/158706/how-to-properly-clean-up-excel-interop-objects
    /// http://stackoverflow.com/questions/19977337/closing-excel-application-with-excel-interop-without-save-message
    /// http://msdn.microsoft.com/en-us/library/h1e33e36.aspx       
    member x.close() =
        match workbook with | Some workbook -> trySave(workbook) | _ -> ignore workbook
        /// may release None:
        releaseComObject sheet |> ignore
        releaseComObject sheets |> ignore
        releaseComObject workbook |> ignore
        match workbooks with | Some workbooks -> workbooks.Close() | _ -> ignore workbooks
        releaseComObject workbooks  |> ignore
        match excel with | Some excel -> excel.Quit() | _ -> ignore excel
        releaseComObject excel |> ignore     

    /// Expert F# 3.0, p. 139
    interface System.IDisposable with
        member x.Dispose() = x.close()

    member x.setSheetByName name =
        match sheets with 
        | Some (sheets) -> sheet <- Some(getSheetByName sheets name)
        | _ -> ignore name

    member x.setSheetByIndex idx = 
        match sheets with 
        | Some (sheets) -> sheet <- Some (getSheetByIndex sheets idx)
        | _ -> ignore idx

    member x.getFrameWithStringHeader (ul: int*int) (lr: int*int) = 
        match sheet with 
        | Some sheet -> getFrameWithStringHeader sheet ul lr
        | _ -> None
        
    member x.getRangeAsArray ulrow ulcol lrrow lrcol : Array option =
        match sheet with 
        | Some sheet -> getRangeAsArray sheet ulrow ulcol lrrow lrcol
        | _ -> None

    member x.getFrameWithHeader ulrow ulcol lrrow lrcol : Frame<int,_> option =
        match sheet with 
        | Some sheet -> getFrameWithHeader sheet ulrow ulcol lrrow lrcol
        | _ -> None