title: String concatenation in Ruby
body: <p>I am looking for a more elegant way of concatenating strings in Ruby.</p>
  
  <p>I have the following line:</p>
  
  <pre><code>source = "#{ROOT_DIR}/" &lt;&lt; project &lt;&lt; "/App.config"
  </code></pre>
  
  <p>Is there a nicer way of doing this?</p>
  
  <p>And for that matter what is the difference between <code>&lt;&lt;</code> and <code>+</code>?</p>