Digital Trunk Class With Helper Classes http://www.eventhelix.com/realtimemantra/object_oriented/object_design_tips_2.htm

digital-trunk-that-delegates-to-helpers.cpp

class DigitTrunk
{
    Status m_status;
    Timeslot m_timeslot[MAX_TIMESLOTS_PER_TRUNK];

    class SignalingHandler
    {
    
       int m_signalingTimeslot;
       int m_signalingStatus;
       . . .
     public:
       void HandleSignalingRequest();
       void SendSignalingIndication();
    };
    
    class ErrorHandler
    {
       int m_errorThreshold;
       int m_localErrorRate;
       int m_remoteErrorRate;
       . . .       
    public:
       void HandleRemoteError();
       void HandleLocalError();
    };
    
   // Helper classes
   SignalingHandler m_signalingHandler;
   ErrorHandler m_errorHandler;
    
public:

    . . .
    void HandleSignalingRequest()
    { m_sigalingHandler.HandleSignalingRequest(); }
    
    void SendSignalingIndication()
    { m_signalingHandler.SendSignalingIndication(); }
    
    . . .
    
    void HandleRemoteError()
    { m_errorHandler.HandleRemoteError(); }
    
    void HandleLocalError()
    { m_errorHandler.HandleLocalError(); }
    
    . . .
};