Type T
    method As Sub(pthis As T Ptr)
End Type

Type S Extends T
    dato As Integer
End Type

Sub TMethod(pthis As T Ptr)
    Print "T method"
End Sub

Sub SMethod(pthis As S Ptr)
    Print "S method, dato = "; pthis->dato
End Sub

Sub CallMethod(pthis As T Ptr)
    pthis->method(pthis)
End Sub

Dim As T tt
tt.method = @TMethod

Dim As S ss
ss.method = @SMethod
ss.dato = 123

Sleep