VB.NET - Extension functions within a class?

Question

I'm trying to make a Class library with a function to convert binary integers to denary, and vice versa, so that I can import it into another project without having to rewrite the function. It works fine, here's part of the class:

Public Class BinaryDenary
    Public Shared Function ToBinary(ByVal DenaryNumber As Integer) As Integer
        Dim Binary As String = ""
        While DenaryNumber > 0
            If DenaryNumber Mod 2 = 1 Then
                Binary = 1 & Binary
            Else
                Binary = 0 & Binary
            End If
            DenaryNumber \= 2
        End While
        Return CInt(Binary)
    End Function
End Class

I've tested it within the project and it works fine.

ToBinary(3) 'Returns 11
ToDenary(110) 'Returns 6

But - mostly for aesthetic reasons - I'd like to be able to use it like an extension method, so that I can take a variable and do this:

NormalInt.ToBinary(3)

But I can't write extension methods inside of a class. Is there any way of doing this? It's not hugely important, but I like to use extension methods where I can.

Answer 1

An extension method written in VB .NET, must be in a Module and be marked with the Extension attribute, something like this:

Public Module BinaryDenary

    <Extension()>
    Function ToBinary(ByVal DenaryNumber As Integer) As Integer
        Dim Binary As String = ""
        While DenaryNumber > 0
            If DenaryNumber Mod 2 = 1 Then
                Binary = 1 & Binary
            Else
                Binary = 0 & Binary
            End If
            DenaryNumber \= 2
        End While
        Return CInt(Binary)
    End Function

End Module

If the module isn't in the same namespace, you should import the namespace where it is used.