title: Comparison : interface methods vs virtual methods vs abstract methods
body: <p>What are the advantages and disadvantages of each of these?</p>
  
  <ul>
  <li>interface methods</li>
  <li>virtual methods</li>
  <li>abstract methods</li>
  </ul>
  
  <p>When one should choose what? What are the points one should keep in mind when making this decision?</p>