あれば便利な気がするけどわざわざ作るほどでもない気もする拡張メソッドたち

Extensions.vb

Public Module Extensions
  <Extension()> _
  Public Function This(Of T)(ByVal target As T) As T
    Return target
  End Function

  <Extension()> _
  Public Function IsNull(Of T As Class)(ByVal target As T) As Boolean
    Return target Is Nothing
  End Function

  <Extension()> _
  Public Function IsNotNull(Of T As Class)(ByVal target As T) As Boolean
    Return target IsNot Nothing
  End Function

  <Extension()> _
  Public Function Or_(Of T As Class)(ByVal target As T, ByVal Func(Of T) factory) As T
    If target Is Nothing Then
        Return factory()
    Else
        Return target
    End If
  End Function

  <Extension()> _
  Public Function IsOneOf(Of T)(ByVal target As T, ParamArray candidates() As T) As Boolean
    Return candidates.Contains(target)
  End Function
End Module

gistfile1.vb

'' 使いみち

'' This/IsNull/IsNotNull は Withと一緒に

With GetFooInstance()
    If .IsNull Then
        Return False
    End If
   .DoSomething()
   list.Add(.This)
End With


'' IsOneOf は If文で

If a.IsOneOf(1, 2, 3) Then '' If a = 1 OrElse a = 2 OrElse a = 3 Then の代わりに
    ...
End If