The following code example is taken from the book
C++ Templates - The Complete Guide, 2nd Edition
by David Vandevoorde, Nicolai M. Josuttis, and Douglas Gregor,
Addison-Wesley, 2017
© Copyright David Vandevoorde, Nicolai M. Josuttis, Douglas Gregor 2017
#include "dynahier.hpp"
#include <vector>
// draw any GeoObj
void myDraw (GeoObj const& obj)
{
obj.draw(); // call draw() according to type of object
}
// compute distance of center of gravity between two GeoObjs
Coord 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 GeoObjs
void drawElems (std::vector<GeoObj*> const& elems)
{
for (std::size_type 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
}