How to implement the factory method pattern in C++ correctly

Question

There\'s this one thing in C++ which has been making me feel uncomfortable for quite a long time, because I honestly don\'t know how to do it, even though it sounds simple:<

Answer 1

Simple Factory Example:

// Factory returns object and ownership
// Caller responsible for deletion.
#include 
class FactoryReleaseOwnership{
  public:
    std::unique_ptr createFooInSomeWay(){
      return std::unique_ptr(new Foo(some, args));
    }
};

// Factory retains object ownership
// Thus returning a reference.
#include 
class FactoryRetainOwnership{
  boost::ptr_vector  myFoo;
  public:
    Foo& createFooInSomeWay(){
      // Must take care that factory last longer than all references.
      // Could make myFoo static so it last as long as the application.
      myFoo.push_back(new Foo(some, args));
      return myFoo.back();
    }
};