////////// file: Tools.h
#include <iostream>
#include <vector>
 
using namespace std;
 
template <typename T> T Sum(vector<T> &V);

///////// file: Tools.cpp
#include "Tools.h"
 
#include <iostream>
#include <vector>
 
using namespace std;
 
template <typename T>
T Sum(vector<T> &V)
{
	T sum = static_cast<T>(0.0);
	for(unsigned int i = 0; i < V.size(); i++)
		sum += V[i];
 
	return sum;
 
}
 
//this is the key line to tell the compiler to actually make this function for unsigned int
template unsigned int Sum<unsigned int>(vector<unsigned int> &V);

template Point Sum<Point>(vector<Point> &V);

////// file: Point.h
#include "Tools.h"
class Point
{
public: 
double x,y,z;
void OutputSum()
{
// do something using a function from Tools here
}
};