/* -*-    Mode:C++; c-basic-offset:4; tab-width:4; indent-tabs-mode:nil -*- */

#include "ns3/callback.h"

#include <cassert>

#include <iostream>

using namespace ns3;

static double 

{

    std::cout << "invoke cbOne a=" << a << ", b=" << b << std::endl;

    return a;

}

class MyCb {

public:

        std::cout << "invoke cbTwo a=" << a << std::endl;

        return -5;

    }

};

int main (int argc, char *argv[])

{

    // return type: double

    // first arg type: double

    // second arg type: double

    Callback<double, double, double> one;

    // build callback instance which points to cbOne function

    // this is not a null callback

    // invoke cbOne function through callback instance

    double retOne;

    retOne = one (10.0, 20.0);

    // return type: int

    // first arg type: double

    Callback<int, double> two;

    MyCb cb;

    // build callback instance which points to MyCb::cbTwo

    // this is not a null callback

    // invoke MyCb::cbTwo through callback instance

    int retTwo;

    retTwo = two (10.0);    

    // invoking a null callback is just like

    // invoking a null function pointer:

    // it will crash.

    //int retTwoNull = two (20.0);

    return 0;

}