>Again, it all depends. #4 might be entirely appropriate if there was no common interface needed among the classes; i.e. if there was no need to treat Vehicles polymorphically. In the VFP world, we don't descend all classes from a common base class, like they do in Smalltalk.

But this is to our disadvantage. I think that if VFP were truer OO, all controls would indeed be subclassed from the same 'control' class. Have you seen all the common code that Ken L put in each base class of the FFC in VFP 6.0? This would not be necessary if all controls shared a point of inheritance.


>#3 might well be the best solution, if the concept of moving doesn't need to be treated polymorophically.

But it does, I think this was the point of the question. If move were too general than the whole point would be moot. This situation is the very basis of the utility of polymorphism.