title: In clean MVP, who should handle combining interactors?
body: <p>I've seen good examples of MVP architecture (<a href="https://github.com/android10/Android-CleanArchitecture" rel="nofollow noreferrer">here</a> and <a href="https://github.com/googlesamples/android-architecture/tree/todo-mvp-clean/todoapp" rel="nofollow noreferrer">here</a>). Both present only simple interactors, but I wonder how to deal with more complex use case, consisting of steps, which are repeated in other use cases.</p>
  
  <p>For example, my API requires token to authenticate any call. I've created an interactor to get that token (<code>GetToken</code>). I want to get user's last login date (<code>GetLastLoginDate</code>) and then fetch a list of changes that occured between that date and now (<code>GetVersionChanges</code>).</p>
  
  <p>Where those interactor should be chained? I want to keep them separate, because some of them are reused in other parts of the code. I've came up with two solutions.</p>
  
  <ol>
  <li><p>Presenter should chain all interactors. This solution works as long the use case is not complex and doesn't have many preconditions. It seems to me it's not the right place, because it burdens presenter with another responsibility.</p></li>
  <li><p>Interactor can use many repositories (no clean architecture rules are broken then). Why not use <code>TokenRepository</code> in other interactors? Because getting token is much more complex than just reaching to repository. Repeating the steps in other interactor does not reuse already existing code.</p></li>
  </ol>
  
  <p>Both solutions have their flaws and are against basic principles (DRY, single responsibility principle).</p>