can i use narrow the Type i want to instantiate with Activator.CreateInstance

Question

i got a large branch of Types that all got the same superclass and interface.

SuperClass: AbstractPackage Interface: IPackage

Types made with this.

Package0....Package723

i use Activator.CreateInstance to create a new instance of the packages, depending og the pattern, recieved from a UDP bytestream.

i got all the registered packages, in a New Dictionary(Of UInt32, Type).

the Uint32 is the package number (0-723) and the Type, is any of the Package0 - Package723 Types.

problem is, that Activator.CreateInstance creates any type of class, and i was wondering if i could narrow the scope Down?

i wanted to make the Dictionary(and Activator.CreateInstance) to only accept Packages. is that posable? thanks

Answer 1

i made a sligth change as Hans Passant pointed out for me, i might have been overthinking it.

here is my new method ( i still need to add all the classes Again, but now i atleast know what types it generate.

Public Function getPackage(ByVal bytes() As Byte) As APackage
        Dim pkgbytes As Byte() = New Byte(3) {}
        Dim o As Integer = 0
        For i As Integer = 8 To 11
            pkgbytes(o) = bytes(i)
            o += 1
        Next

        Dim package As APackage

        Dim iT As UInt32 = UByteChunk.getUInt32(pkgbytes)
        Select Case iT
            Case 0
                '0 Acknowledge
                package = New Package0(bytes)
            Case 152
                '152 EventCall
                package = New Package152(bytes)
            Case 157, 162, 165, 166
                ' 157 Event Extension
                ' 162 Event Delta Call
                ' 165 
                ' 166 Event Call Logging
                package = New PackageCall(bytes)
            Case 174
                '174 Event Targeting
                package = New Package174(bytes)
            Case 187, 188
                '187 SIP Rx
                '188 SIP Tx
                package = New PackageSIP(bytes)
            Case 93, 501, 502, 626
                '93 Version
                '501 Info
                '502 Info 2
                '626 License
                package = New PackageText(bytes)
            Case 563
                '563 System Endpoint
                package = New Package563(bytes)
            Case Else
                package = New PackageDefault(bytes)
        End Select

        Return package
    End Function