The following code example is taken from the book
Object-Oriented Programming in C++
by Nicolai M. Josuttis, Wiley, 2002
© Copyright Nicolai M. Josuttis 2002
// draw any geometric object
template <typename GeoObj>
void myDraw (const GeoObj& obj)
{
obj.draw();
}
// calculate distance between two geometric objects
template <typename GeoObj1, typename GeoObj2>
Coord distance (const GeoObj1& x1, const GeoObj2& x2)
{
Coord a = x1.position() - x2.position();
return a.abs();
}
// output homogenous set of geometric objects
template <typename GeoObj>
void drawElems (const std::vector<GeoObj>& elems)
{
for (unsigned i=0; i<elems.size(); ++i) {
elems[i].draw();
}
}
int main()
{
Line l;
Circle c;
Circle c1, c2;
myDraw(l); // myDraw<Line>(GeoObj&) => Line::draw()
myDraw(c); // myDraw<Circle>(GeoObj&) => Circle::draw()
distance(c1,c2); // distance<Circle,Circle>(GeoObj&,GeoObj&)
distance(l,c); // distance<Line,Circle>(GeoObj&,GeoObj&)
// std::vector<GeoObj*> coll; // ERROR: no inhomogenous collection possible
std::vector<Line> coll; // OK: homogenous collection
coll.push_back(l); // insert line
drawElems(coll); // draw collection
}