Question

I am trying to create a derived class object in base class method.

I am getting the error as mentioned above. Below is a code snippet.

Any help?

 ---- Voip_connection.hh ---- 

   #ifndef __VOIP_CONNECTION_HH
   #define __VOIP_CONNECTION_HH

 class VoipConnection {
 public:

VoipConnection();
VoipConnection (ConnectionState* cs);

void update_last_data_rcvd_time() { last_data_rcvd_time_ = msec_time(); }
uint64_t last_data_rcvd_time() { return last_data_rcvd_time_; }
void set_voip_proto(int proto) { voip_proto_ = proto;}

~VoipConnection()
{
    --nx_stat().act_connections;
    voip_idle_wait_timer_clear();
    sv_streaming_offset_ = 0;
    cl_streaming_offset_ = 0;
}


// Lots and Lots of Other stuff



  }


----Voip_sip.hh -----

#ifndef __VOIP_SIP_HH
#define __VOIP_SIP_HH
#include "voip_connection.hh"

class SipObj: public VoipConnection 
{

    /* stuff */
} 


--- Voip_connection.cc ----
#include "voip_connection.hh"

class SipObj; // Tried this in .hh file as well. 

VoipConnection::voip_process_pdu(bool from_client) 
{
 SipObj sip;
 sip.process(datap, &pdu_len);
 }

Answer 1

In order to instantiate a class, you need the complete type. This

SipObj sip;

requires the full definition of SipObj. A simple forward declaration won’t do, you need to include the appropriate header.

In general, I would say that having a base class depend explicitly on one of it’s derived types is a pretty bad idea.

Concerning the other error you report, it simply says that class VoipConnection has no default constructor. So you will have to provide one.