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.

score 17 · Answer 1 · edited Jul 19 '13 at 23:37

17

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.

edited Jul 19 '13 at 23:37

Tom Blodget

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answered Jul 19 '13 at 23:02

Zach dev

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What is the Namespace? The Module? Do I import it the same way I import a class? – Lou Jul 20 '13 at 10:33
Namespaces it's another way to organize your code, read about it here [Understanding Assembly and Namespace](http://msdn.microsoft.com/en-us/library/ms973231.aspx) A module is a logical collection code within an assembly, read about it here [What is a module in .NET?](http://stackoverflow.com/questions/645728/what-is-a-module-in-net) – Zach dev Jul 20 '13 at 12:55
So, just to clarify: I should write the functions within a new module in a separate Namespace? And should this be in a separate .vb file? – Lou Jul 20 '13 at 19:18
1

should or should not, depends on good practices that you apply to your project, you can research and explore about project architecture for more details – Zach dev Jul 22 '13 at 21:54

VB.NET - Extension functions within a class?

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