Currently there are a multiple ways to yield, hold a pointer to a client cursor, delete/erase a client cursor, etc and in some cases these alternative routines have different nonobvious properties. I think some of these implementations can be unified and their operations can be simplified.

Also the current implementation will explicitly delete a ClientCursor object once it becomes invalid, often leaving dangling invalid pointers that must be handled properly. This can make yielding and other ClientCursor operations more difficult to implement than necessary.