title: Angular2 "Services" how to @inject one service into another (singletons)?
body: <p>How would I go about injecting one service into another? Let's for example say I have a Collection that requires another Collection (TeamCollection => PlayerCollection). Currently I just create two separate Collections and use something like:</p>
  
  <pre><code>import {PlayerCollection} from "&lt;&lt;folder&gt;&gt;/player";
  </code></pre>
  
  <p>But this requires me to write my own singleton getInstance code within Typescript for each and every service that I want to be a singleton instance. </p>
  
  <p>What is the correct way to do this? I want to have both singletons within my Components and be able to @Inject one service into another using the constructor syntax, without creating a new instance of the singletons.</p>
  
  <pre><code>class TeamCollection {    
      constructor(@Inject(PlayerCollection): PlayerCollection) {}
  }
  </code></pre>