title: How to init a class static variable with Future in Dart?
body: <p>As we know, there is a <code>getApplicationDocumentsDirectory()</code> function that returns a <code>Future&lt;Directory&gt;</code> in package <code>path_provider</code>.
  But now I want to init a static variable through it:</p>
  <pre><code>class Settings {
    static final Directory rootDirectory = /*The documents directory*/;
  }
  </code></pre>
  <p>I can't use <code>await</code> here. How can I do?</p>