Hashtables full of record-like objects are the usual problem. I often find myself throwing records into a hashtable and then keying it by one of its properties,

Hashtables full of record-like objects are the usual problem. I often find myself throwing records into a hashtable and then keying it by one of its properties, and that means it's a simple primitive and there may be many of the same type. If I've a record with a half-dozen int properties that are semantically IDs, I have to clarify which is the key for this hashtable.