title: Is it possible to add a dynamic class to host in Angular 2?
body: <p>I know that in Angular2 I can add a class 'red' to a component's selector element by doing this:</p>
  
  <pre><code>@Component({
      selector: 'selector-el',
      host: {
          '[class.red]': 'true'
      },
      ...
  })
  </code></pre>
  
  <p>I'm wondering whether there's a way to add a <em>dynamic</em> class to a host, similar to what you would do with NgClass (I know NgClass is not actually supported, I'm looking for possible solutions):</p>
  
  <pre><code>@Component({
      selector: 'selector-el',
      host: {
          '[NgClass]': 'colorClass'
      },
      ...
  })
  ...
  constructor(){
      this.colorClass = 'red';
  }
  </code></pre>