title: How to create an array or group of Directives in Angular 2
body: <p>I currently have a module with a Component and a Directive which supports the Component in my Angular 2 app. For the user to use this Component they have to import both the Component and the Directive. Is there a way that I can group them into something like <code>ROUTER_DIRECTIVES</code></p>
  
  <p>For eg:</p>
  
  <pre><code>import {Component, HostListener, Directive} from "angular2/core";
  
  @Component({
      selector: "my-dropdown",
      templateUrl: "./dropdown.html",
      styleUrls: ["./dropdown.css"]
  })
  export class Dropdown {
      //code
  }
  
  @Directive({
      selector: ".my-dropdown-toggle"
  })
  export class DropdownToggle{
  
      //code
  }
  </code></pre>
  
  <p>To use this the user has to import like this:</p>
  
  <pre><code>@Component({
      moduleId: module.id,
      directives: [Dropdown,DropdownToggle,ROUTER_DIRECTIVES],
      templateUrl: "./dropdown-sample.html"
  })
  export class DropdownAngularDemo {
  }
  </code></pre>
  
  <p>I want to know if I can group <code>Dropdown</code> and <code>DropdownToggle</code> into an array like <code>ROUTER_DIRECTIVES</code></p>