>I know we can do everything with VFP :), but how did we add a method on the fly ?

The question is, should you be able to add a method to a class at runtime? Most OO design and implementation would say no, since that means you start doing object programming rather than class based OOP. It was intentional in VFP 3.0 and since then to not add the ability to do this, as well as not adding the ability to support multiple inheritance. And considering that the VFP community has not been asking for these features, I think the decisions have been validated as the right thing to do. But as you say, you can do everything with VFP (well, almost). With VFP today, you can access/assign methods to simulate modifying and extending a object instance from it's class defintion at runtime.