Question

I created a class which holds data of type and returns an vector on request.
But somehow the following error occurs:

error C2259: 'CAcceptor' : cannot instantiate abstract class
          due to following members:
          'void CDataAndEvent<C>::InitQueue(void)' : is abstract
          with
          [
              C=SOCKET
          ]
          see declaration of 'CDataAndEvent<C>::InitQueue'         with
          [              C=SOCKET
           ]

code for the class:

#pragma once
#include <IncStandard.h>
#include <IncWinsock.h>
#include <IncStatus.h>

//Class which hold an Input and Output vector
//and the corresponding events
template<class C>
class CDataAndEvent
{
public:
 CDataAndEvent(void);
 virtual ~CDataAndEvent(void);

 //Access functions
 //Vectors
 virtual Inc::STATS GetInData(__out std::vector<C>&);
 virtual Inc::STATS GetOutData(__out std::vector<C>&);
 virtual Inc::STATS AddDataIn(__in const C&);
 virtual Inc::STATS AddDataOut(__in const C&);
 //Queues
 virtual HANDLE GetOutEvent() { return m_hEventOut; };
 virtual HANDLE GetInEvent() { return m_hEventIn; };

protected:
 //Make this class non-instanceable
 virtual void InitQueue() = 0;

private:
 //Input-/Output Vector
 std::vector<C> m_vecIn;
 std::vector<C> m_vecOut;

 //Events for the input- and output vector
 HANDLE m_hEventIn;
 HANDLE m_hEventOut;

 //Indicators
 bool m_bNewIn;
 bool m_bNewOut;
};

template<class C>
CDataAndEvent<C>::CDataAndEvent(void) : m_bNewIn(false), m_bNewOut(false)
{
 //create events
 m_hEventIn = CreateEvent(NULL, TRUE, FALSE, NULL);
 m_hEventOut = CreateEvent(NULL, TRUE, FALSE, NULL);
}

template<class C>
CDataAndEvent<C>::~CDataAndEvent(void)
{
}

template<class C>
Inc::STATS CDataAndEvent<C>::GetOutData(std::vector<C>& vec)
{
 if(!m_bNewOut)
  return Inc::NEMPTY;

 vec = m_vecOut;
 m_vecOut.clear();

 m_bNewOut = false;
 ResetEvent(m_hEventOut);

 return Inc::SOK;
}

template<class C>
Inc::STATS CDataAndEvent<C>::GetInData(std::vector<C>& vec)
{
 if(!m_bNewIn)
  return Inc::NEMPTY;

 //copy
 vec = m_vecIn;

 //clear the read data
 m_vecIn.clear();

 //no new data
 ResetEvent(m_hEventIn);
 m_bNewIn = false;

 return Inc::SOK;
}

template<class C>
Inc::STATS CDataAndEvent<C>::AddDataOut(const C& str)
{
 m_vecOut.push_back(str);

 m_bNewOut = true;

 SetEvent(m_hEventOut);

 return Inc::SOK;
}

template<class C>
Inc::STATS CDataAndEvent<C>::AddDataIn(const C& str)
{
 m_vecIn.push_back(str);

 //new data available
 m_bNewIn = true;
 SetEvent(m_hEventIn);

 return Inc::SOK;
}

Anyone got a clue why this happens?…

The CAcceptor-class is defined as the following

#pragma once
#include "connection.h"
#include "DataAndEvent.h"
class CAcceptor :
 public CConnection, public CDataAndEvent<SOCKET>
{
public:
 CAcceptor(void);
 virtual ~CAcceptor(void);

 //Bind the port
 Inc::STATS BindSocket(const std::string& strPort);

 Inc::STATS Start();  //Start accepting
 Inc::STATS Stop();  //Stop accepting

private:
 //Send data: not needed for the acceptor
 Inc::STATS _SendData(sockaddr* pTarget, int tolen, std::string& strData) {return Inc::EUNKNOWN;};
 //Recv data: not needed for the acceptor
 Inc::STATS _RecvData(sockaddr* pSender, int* tolen, std::string& strData) {return Inc::EUNKNOWN;};

 //Create sockets
 Inc::STATS CreateSocket();
 //Delete Sockets
 Inc::STATS DeleteSocket();

 //Thread stuff
 HANDLE m_hThread;  //Thread handle for the auto mode thread
 friend DWORD WINAPI AutoModeThread(void*);  //Auto mode thread
};

and as far as i checked it overrides the pure virtual functions from CConnection:

#pragma once

//Headers
#include <IncStatus.h>
#include <IncWinsock.h>
#include <IncStandard.h>

class CConnection
{
public:
 CConnection();
 virtual ~CConnection(void);

 //TEST: Bind socket contained by m_mapSocketContainer
 virtual Inc::STATS BindSocket(const std::string& strPort) = 0;

 //Resolve Target Address
 addrinfo* ResolveAddress(const std::string& strAddress, const std::string& strPort);

protected:
 //Sockets
 SOCKET m_Socket;

 //Target Address
 addrinfo* m_pTargetAddress;

 //Socket
 //Creates the sockets needed
 //Will be called automatically by the constructor
 virtual Inc::STATS CreateSocket() = 0;
 //closes the sockets
 //Will be called automatically by the destructor
 virtual Inc::STATS DeleteSocket() = 0;

 //Data Transmission User Request
 virtual Inc::STATS _SendData(sockaddr* pTarget, int tolen, std::string& strData) = 0;
 virtual Inc::STATS _RecvData(sockaddr* pSender, int* fromlen, std::string& strData) = 0;

private:
 //Winsock startup & cleanup
 //Start / Stop
 Inc::STATS StartWinsock();
 Inc::STATS StopWinsock();

 WSADATA m_Wsa;
 unsigned short m_wWsaVer;

 static bool bWinsockRunning;
};

Thank You!…

Answer 1

All classes derived from the class template CDataAndEvent<T> including CAcceptor needs to define InitQueue() (which is a pure virtual function making the class template an abstract one). I don’t see any CAcceptor::InitQueue definition though in the code you posted.