> On Mar 27, 2010, at 15:43 , Darren Duncan wrote: > > For example, say you want to define a graph of some kind, and for > > elegance you have a separate container and node and side classes,
On Sat, 27 Mar 2010, Brandon S. Allbery KF8NH wrote: > This sounds like a hackaround for an incomplete implementation of ADTs. No, it's simply a reflection that the one-to-one relationship between the attributes of a single storage object is too simplistic to use as the *only* encapsulation boundary. Of course, that points towards having access limits that depend not just on the type, but on the specific object: in Darren's example, nodes should be able to see the details of the edges and faces they're attached to, but probably not any other edges or faces. And definitely not the edges or faces in some completely disconnected mesh or network. A connected mesh or network is a reasonable ADT, but to implement it you're going to want several classes. The mesh-object-as-a-whole is the appropriate encapsulation boundary. If we had a really sophisticated ADT that could represent a "Network", that would indeed solve the encapsulation problem. So what tools are we going to need to build such an ADT? Well, privacy, trust, ... -Martin
