title: How to set a fixed value to fields to a type?
body: <p>If I have this hierarchy of classes:</p>
  
  <pre><code>Class Shape
  {
  public bool closedPath;
  }
  
  class Circle : Shape
  {
  }
  class Line: Shape
  {
  }
  </code></pre>
  
  <p>Here I know that all circles are closed paths.
  How to set the value of <code>closedPath</code> field to these defaults without the need to assign its value when instantiating an object of that said class?</p>