#include <boost/shared_ptr.hpp>

#include <iostream>

class Base {
public:
  virtual void foo(void) {
    std::cout << "Base!\n";
  }
};

class A : public Base {
public:
  A(void) {}
  A(boost::shared_ptr<Base> o) {}

  virtual void foo(void) {
    std::cout << "A!\n";
  }
};

boost::shared_ptr<A>
make(boost::shared_ptr<Base> pb) 
{
  std::cout << "Convert!\n";
  boost::shared_ptr<A> p(new A(pb));
  return p;
}

boost::shared_ptr<Base> foo(boost::shared_ptr<Base> pb)
{
  boost::shared_ptr<Base> p(boost::dynamic_pointer_cast<A>(pb) ?
                            pb : make(pb));
  return p;
}

int main(void) 
{
  boost::shared_ptr<A> p(new A);
  boost::shared_ptr<Base> pb(new Base);
  std::cout << "Pass p\n";
  boost::shared_ptr<Base> result = foo(p);
  result->foo();
  std::cout << "Pass pb\n";
  result = foo(pb);
  result->foo();

  return 0;
}