Errors in TCPStream

[Tommi Mäkitalo]

Hi,

I am working on a FTP-class and use CommonC++ as a base. But I 
discovered difficulties catching errors. Here is a example-code:

 TCPStream* socket;
 try
 {
   cout << "connecting" << endl;
   socket = new TCPStream(InetHostAddress("localhost"), 4711);

   cout << "delete" << endl;
   delete socket;
   cout << "OK" << endl;
 }
 catch(Socket* s)
 {
   cerr << "socket error " << s->getErrorNumber() << endl
        << s->getErrorString() << endl;
 }

If there is no server listening I should get a SOCKET_CONNECT_FAILED. 
But the problem is, that you use the this-pointer in socket-class to 
throw the exception. But it isn't valid in the catch-block, because the 
constructor isn't fully executed. It makes no difference when I declare 
my socket on the stack like this:

 try
 {
   cout << "connecting" << endl;
   TCPStream socket(InetHostAddress("localhost"), 4711);
   cout << "OK" << endl;
 }
 catch(Socket* s)
 {
   cerr << "socket error " << s->getErrorNumber() << endl
        << s->getErrorString() << endl;
 }

It is better to create a exception-class and throw that. Maybe you can 
derive from std::exception.

Like this:

class SocketException : public std::exception
{
   sockerror_t errid;
   std::string errstr;
 public:
   SocketException(sockerror_t err, const char* errs)
     : errid(err),
       errstr(errs)
       { }
   virtual const char* what() const
   { return errstr.c_str(); }
   sockerror_t getErrorNumber() const  { return errid; }
   std::string getErrorString() const  { return errstr; }
};

Now this should work:

 try
 {
   cout << "connecting" << endl;
   TCPStream socket(InetHostAddress("localhost"), 4711);
   cout << "OK" << endl;
 }
 catch(SocketException s)
 {
   cerr << "socket error " << s->getErrorNumber() << endl
        << s->getErrorString() << endl;
 }

Or even:

 try
 {
   cout << "connecting" << endl;
   TCPStream socket(InetHostAddress("localhost"), 4711);
   cout << "OK" << endl;
 }
 catch(exception e)
 {
   cerr << "exception occured: " << e.what() << endl;
 }

By the way, is there a mailing-list for CommonC++ users, where I can 
subscribe?

Tommi Mäkitalo