Constructor.
Adds a client to the set.
foreach operator over registered clients.
Removes a client from the set.
Adds a client to the set of registered clients. Calls the client's registered() method, then calls the abstract add_() method.
Removes a client from the set of registered clients. Calls the client's unregistered() method, then calls the abstract remove_() method.
Class to keep track of a set of registered clients, including the capacity to iterate over them. This class is used only in debug builds, where it is useful to be able to tell exactly which clients are registered.