Question

I have a question related with VB.Net Code.

I see that the DataTable we can use:

DataTable(0) ' This return a DataRow with the selected index

In the intellisense I see that this functionality can achieve with a extension… but, If I create a extension, always I need refer the Extension before to use it

Public Module asdadsdas
    <System.ComponentModel.EditorBrowsable(System.ComponentModel.EditorBrowsableState.Always)>
    <System.Runtime.CompilerServices.ExtensionAttribute()>
    Friend Function MyExt(ByVal pMyObject As MyObject, ByVal ColumnName As String) As MyObject.ColumnData

        Return pMyObject.Columns(0)

    End Function
End Module

Public Class MyObject
    Friend Structure ColumnData
        Friend vNombre As String
        Friend vApellido As String
        Friend vTelefono As String

        Public Property Nombre As String
            Get
                Return Me.vNombre
            End Get
            Set(ByVal value As String)
                Me.vNombre = value
            End Set
        End Property

    End Structure

    Friend Columns() As ColumnData

    Public Sub add(ByVal MyColumn As String)
        ReDim Columns(0)
        Columns(0).vNombre = MyColumn
    End Sub

End Class

Public Class Form1

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Dim Test As New MyObject
        Test.add("TEST 001")
        ' HERE IS THE PROBLEM
        Test("TEST 001")
        ' CORRECT USE
        Test.MyExt("TEST 001")
    End Sub
End Class

Now, my concrete question: How I can make a default extension in a specific Object?

---

@competent_tech: man you are a genius… thanks by your comment!

This is the solution of my problem:

Public Class ColumnData
Friend Name As String
Friend LastName As String
Friend Phone As String

End Class

Public Class MyColumns
Friend Data() As ColumnData

Default Property Item(ByVal ColumnName As String) As ColumnData
    Get
        Return Data(0)
    End Get
    Set(ByVal value As ColumnData)

    End Set
End Property

Public Sub add(ByVal Name As String, ByVal LastName As String, ByVal Phone As String)
    If Data Is Nothing Then
        ReDim Data(0)
        Data(0) = New ColumnData
    End If

    With Data(0)
        .Name = Name
        .LastName = LastName
        .Phone = Phone
    End With


End Sub

End Class

Public Class Form1

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
    Dim Test As New MyColumns

    Test.add("Name 001", "bolanos.m", "500-2004-1000")

    Debug.Print(Test("Name 001").LastName & " - " & Test("Name 001").Phone)
    ' bolanos.m - 500-2004-1000

    Test("Name").LastName = "BOLANOS.M MODIFY"

    Debug.Print(Test("Name 001").LastName & " - " & Test("Name 001").Phone)
    ' BOLANOS.M(MODIFY - 500 - 2004 - 1000)
End Sub

End Class

Answer 1

Why not just add default properties to the MyObject class?

Default Public Property IndexedColumn(index As String) As ColumnData
    Get
        Return Columns(index)
    End Get
    Set(value As ColumnData)
        Columns(index) = value
    End Set
End Property
Default Public Property IndexedColumn(index As Integer) As ColumnData
    Get
        Return Columns(index)
    End Get
    Set(value As ColumnData)
        Columns(index) = value
    End Set
End Property

You will need to change the exposure level of the structure and the access will be:

    Dim oColumnData = Test("TEST 001")