title: Dart Angular 2 annotation how do they work?
body: <p>I'm currently playing with the Dart version of Angular 2.</p>
  
  <p>I have seen that the library is using a lot of Metadata as <code>@Component</code> for example.</p>
  
  <p>I would like to know how are those directives working? </p>
  
  <p>I went on <a href="http://www.darlang.org" rel="nofollow">http://www.darlang.org</a>. They explain how to define an annotation but not how to use it to construct an object as it is done in angular.io.</p>
  
  <p>Could someone explain how the magic is working?</p>