title: How do I initialize a property that depends on another property, when I don't have access to self yet?
body: <p>I have two properties in my class. See this terrible example:</p>
  
  <pre><code>var length
  var doubleLength
  </code></pre>
  
  <p>How do I initialize <code>doubleLength</code> based on <code>length</code>?</p>
  
  <pre><code>init() {
      self.length = ...
      self.doubleLength = self.length * 2
  
      super.init()
  }
  </code></pre>
  
  <p>I get an error that I can't access <code>self</code> before I call <code>super.init()</code>. Well I need to set all my variables before I can even call <code>super.init()</code> so what am I supposed to do?</p>