title: How does typeid work and how do objects store class information?
body: <p><a href="http://en.wikipedia.org/wiki/Typeid" rel="noreferrer">http://en.wikipedia.org/wiki/Typeid</a></p>
  
  <p>This seems to be a mystery to me: how does a compiler stores information about the type of an object ? Basically an empty class, once instantiated, has not a zero size in memory.</p>