Do you mean you want your vector to be heterogenous, i.e. containing different types? If so, you can use boost::variant: typedef boost::variant shape_type; // square, circle, triangle may be unrelated types providing show_me() method std::vector shapes; struct drawer : boost::static_visitor<> { template<typename shape> void operator()(shape &sh) const { sh.show_me(); } }; int main() { shapes.push_back(triangle()); shapes.push_back(circle()); BOOST_FOREACH(std::vector::reference shape, shapes) boost::apply_visitor(drawer(), shape); } 2008/7/10, Peng Yu :

Hi,

The following program uses virtual functions. Essentially I need to go through all the pairs in 'v'.

Since I have already know what are in v at compile time. I would like to convert the dynamic polymorphism to template. Therefore, the runtime would be better. I think this should be done with the help of boost::mpl. But I'm not sure how to do it. Would you please help me?

Thanks, Peng

#include <iostream> #include <vector> #include

struct shape { virtual void show_me() const = 0; virtual ~shape() { } };

struct square : public shape { void show_me() const { std::cout << "square"; } };

struct circle : public shape { void show_me() const { std::cout << "circle"; } };

struct triangle : public shape { void show_me() const { std::cout << "triangle"; } };

int main() { std::vector v; { boost::shared_ptr<shape> s(new square); v.push_back(s); } { boost::shared_ptr<shape> s(new circle); v.push_back(s); } { boost::shared_ptr<shape> s(new square); v.push_back(s); } { boost::shared_ptr<shape> s(new triangle); v.push_back(s); }

for(std::vector::const_iterator it = v.begin(); it != v.end(); ++ it) { for(std::vector::const_iterator it2 = it + 1; it2 != v.end(); ++ it2) { (*it)->show_me(); std::cout << " vs. "; (*it2)->show_me(); std::cout << std::endl; } } } _______________________________________________ Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users