Angus <anguscomber@gmail.comwrote in news:1187798603.500722.26020
@m37g2000prh.googlegroups.com:
Quote:
I am designing an FTP server and with FTP commands are dispatched on
one port and the actual data transmission on another.
>
So I thought I would have a CFTPControl class for handlng the commands
and a CFTPData class for the actual data transmission.
>
But CFTPControl needs to know when the data transmission has
completed. What is the best way to handle this interaction between
the classes?
>
It seems like the Observer pattern is a natural fit.
class CFTPData;
class IDataReport
{
public:
virtual void OnDataDone(CFTPData *) = 0;
virtual ~IDataReport() {}
};
class CFTPData
{
IDataReport * m_pObserver;
public:
void RegisterObserver(IDataReport * pObserver)
{ m_pObserver = pObserver; }
void Process()
{ /* Do stuff */ if (m_pObserver) m_pObserver->OnDataDone(this); }
};
class CFTPControl : private IDataReport
{
public:
void Observe(CFTPData * pSubject)
{ pSubject->RegisterObserver(this); }
private:
void OnDataDone(CFTPData * pSubject)
{ /* wheee the data is done */ }
};
I don't know that you strictly need the pointer to the subject, but I
have yet to use the Observer pattern where knowing which object was
notifying you wasn't important in some fashion. Obviously, the single
pointer can be a vector of pointers if you are going to allow more than
one observer. The functionality in the Observe() method can be done
anyplace you have a pointer to the subject, so don't take the above too
literally.
joe
