Static variable in module sample Omnet++

SessionManager.cc

#include "SessionManager.h"
using namespace sdicn;

Define_Module(sdicn::SessionManager);

int SessionManager::binderCounter = 0;
vector<SessionManager::SessionBinding> SessionManager::bindings = vector<SessionBinding>();

void SessionManager::initialize()
{
    if (binderCounter == 0) {
        bindings = vector<SessionBinding>();
    }

    ++binderCounter;
}

SessionManager::~SessionManager()
{
    --binderCounter;
}

SessionManager.h

#pragma once

#include <tuple>
using namespace std;

#include <omnetpp.h>
using namespace omnetpp;

namespace sdicn {

class SessionManager : public cSimpleModule {
protected:
    typedef tuple<string, unsigned, int> SessionBinding; // serviceName, consumerIp, bsIndex

    static int binderCounter;
    static vector<SessionBinding> bindings;
  
    virtual void initialize() override;
    virtual ~SessionManager();
};

}