Telling A Generic Function That It Will Use An Interface With A Constructor?

i've been trying to toy around with generics in vb.net in an example project. At the moment, it looks like this:

I have an interface called IRow (and a class that implements it as a Datarow).

A second interface is ICanGetByRow, which looks like this:

Public Interface ICanGetByRow(Of T)
Function GetByRow(ByVal Row As IRow) As T
End Interface

The function simply takes an IRow and converts it to T. Thats easy enough. Now, for easier access, i want to implement a function in the IRow interface which takes the row and converts it into said ICanGetByRow.

My interface was enhanced by the following function

Function GetObj(Of T As ICanGetByRow(Of T))() As T

You can probably see the problem. If i implemented it like this:

Public Function GetObj(Of T As ICanGetByRow(Of T))() As T Implements IRow.GetObj
Dim foo As New T
foo.GetByRow(Me)
Return foo
End Function

i wouldn't be allowed to construct a new T, and when i tried to make it work by telling the generic function that my interface has a constructor, he wouldn't let me invoke GetByRow anymore.

Public Function GetObj(Of T As New, ICanGetByRow)() As T Implements IRow.GetObj
Dim foo As New T
foo.GetByRow(Me)
Return foo
End Function

how to tell a generic function that it will get a ICanGetByRow(of T) which has a constructor