title: C++ where I'll need local extension or foreign method?
body: <p>I'm not familiar with C++ enough to know where those 2 very similar refactorings (introduce local extension and introduce foreign method) will be needed. I know cases that forces to use those, but I can't figure sample classes that will need this "trick". I'm making C++ refactoring tutorial, to help new developers, but it looks like I need yours help too :)</p>
  
  <p>If you used it, please tell me in where and why. Thanks in advance.</p>