/* The following code example is taken from the book * "C++ Templates - The Complete Guide" * by David Vandevoorde and Nicolai M. Josuttis, Addison-Wesley, 2002 * * (C) Copyright David Vandevoorde and Nicolai M. Josuttis 2002. * Permission to copy, use, modify, sell and distribute this software * is granted provided this copyright notice appears in all copies. * This software is provided "as is" without express or implied * warranty, and with no claim as to its suitability for any purpose. */#include "dynahier.hpp"#include <vector>// draw any GeoObjvoid myDraw (GeoObj const& obj){    obj.draw();            // call draw() according to type of object}// process distance of center of gravity between two GeoObjsCoord distance (GeoObj const& x1, GeoObj const& x2){    Coord c = x1.center_of_gravity() - x2.center_of_gravity();    return c.abs();        // return coordinates as absolute values}// draw heterogeneous collection of GeoObjsvoid drawElems (std::vector<GeoObj*> const& elems){    for (unsigned i=0; i<elems.size(); ++i) {        elems[i]->draw();  // call draw() according to type of element    }}int main(){    Line l;    Circle c, c1, c2;    myDraw(l);            // myDraw(GeoObj&) => Line::draw()    myDraw(c);            // myDraw(GeoObj&) => Circle::draw()    distance(c1,c2);      // distance(GeoObj&,GeoObj&)    distance(l,c);        // distance(GeoObj&,GeoObj&)    std::vector<GeoObj*> coll;  // heterogeneous collection    coll.push_back(&l);         // insert line    coll.push_back(&c);         // insert circle    drawElems(coll);            // draw different kinds of GeoObjs}