>>What if a new security object provides new methods and properties which should be accessed through the security manager ?

>In that case security manager would need to be updated to hoinor the interface of the new object. It would not mean that security manager would need to change its interface though.

That may be the main difference between the two different aproaches, and this is the main difference between VFP's inheritance and the VB interface appraoch.
Your' trying to simulate inheritance, but you've got to mannually take care of some things to accomplish the same inheritance VFP does natively.

Because the first example seems just more OO to me, I would not even consider the second, if there are no complications in the first one (for example multiple inheritance).

This is the main point JVP and I argued about whether or not inheritance is of any value in a middle tier. John, solves inheritance related problems by using interfaces and doesn't call this inheritance. In fact he's right this isn't inheritance, but the motive to apply this construction is the missing of inheritance in the first place. I've not seen many VFP code which applies the second approach.

Therefore I can only conclude inheritance can be of (a significant) value in the middle tier.

Walter,