title: How to add a new property to a class using class decorator?
body: <p>How can I add a new property to a class using a class decorator?</p>
  
  <p>Code for example:</p>
  
  <pre><code>@MyClassDecorator
  class MyClass {
      myFirstName: string;
      myLastName: string;
  }
  
  // I need something like this:
  function MyClassDecorator (target: any): any {
      target['myNickname'] = 'Gambler';
  }
  
  let myClass = new MyClass();
  console.log(myClass['myNickname']); // expecting "Gambler" but got "undefined"
  </code></pre>
  
  <p>How to fix this code?</p>
  
  <p>Is it possible at all to add a property to a class using decorator?</p>
  
  <p>Thanks!</p>