(.NET) IntelliSense difference of Extension Method name in Statement Completion for VB and C#.

Recently, I noticed a strange behavior for looking up name of Extension Method in VB and C#.

That is, if you overwrite a method or a property by using extension, your extension will not displayed for IDE IntelliSense.

But if you declared a new generic method, you will notice a small difference.

1. Overwrite the existed property via VB. ( Actually, C# is the same. )

a) Create a VB Console Application.

b) Paste below code at the end of editor.

Public Class Lucas
    Private n_test As String

    Public Property Test() As String
        Get
            Return n_test
        End Get
        Set(ByVal value As String)
            n_test = value
        End Set
    End Property
End Class

Module LucasExtension
    <Extension()> _
    Public Function Test(Of T)(ByVal aParam As Lucas) As String
        Return "Hello, Lucas Luo!"
    End Function
End Module

c) Type below code inside Main in Module1.

        Dim olucas = New Lucas()
        olucas.

d) Notice the IntelliSense.

2. Verify the Extension Method in IntelliSense between C# and VB via generic type.

a) Create a C# Console Application.

b) Type below code under class Program.

public class Lucas
    {
        public string Test { get; set; }
    }

    public static class LucasExtension
    {
        public static string TestExtension<T>(this Lucas aParam)
        {
            return "Hello, Lucas Luo!";
        }
    }

c) Type below code inside in Pragram class and notice the IntelliSense.

    class Program
    {
        static void Main(string[] args)
        {
            Lucas olucas = new Lucas();
            olucas.
        }
    }

d) See below picture, you'll see the "<>" for the generic type of extension method.

e) Now, let's see what's the behavior in VB.

f) Create a vb console application and add the extension method based on above steps.

g) Slit change on the generic type of extension method. We use "Of" to represent the generic type that you want to pass. See below code.

Module LucasExtension
    <Extension()> _
    Public Function TestExtension(Of T)(ByVal aParam As Lucas) As String
        Return "Hello, Lucas Luo!"
    End Function
End Module

h) Type the same VB code as in the first sample inside Main in Module1.

i) See the IntelliSense of VB extension method. You'll find that there isn't any "<>" string, or "Of" string displayed in VB intellisense.