/* -*-	Mode:C++; c-basic-offset:8; tab-width:8; indent-tabs-mode:t -*- */

#include <cassert>

#include <iostream>

using namespace yans;

static double 

cb_one (double a, double b)

{

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

	return a;

}

class MyCb {

public:

	int cb_two (double a) {

		std::cout << "invoke cb_two 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 cb_one function

	one = make_callback (&cb_one);

	// this is not a null callback

	assert (!one.is_null ());

	// invoke cb_one function through callback instance

	double ret_one;

	ret_one = 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::cb_two

	two = make_callback (&MyCb::cb_two, &cb);

	// this is not a null callback

	assert (!two.is_null ());

	// invoke MyCb::cb_two through callback instance

	int ret_two;

	ret_two = two (10.0);	

	two = make_null_callback<int, double> ();

	// invoking a null callback is just like

	// invoking a null function pointer:

	// it will crash.

	//int ret_two_null = two (20.0);

	assert (two.is_null ());

	return 0;

}