title: Ruby: how to insert a conditional into a string concatenation
body: <p>In a string concatenation, is it possible to include a conditional directly into the statement? </p>
  
  <p>In the example below, I want <code>"my dear"</code> to be concatenated only if the <code>dear</code> list is not empty.</p>
  
  <pre><code>dear = ""
  
  string = "hello" + " my dear" unless dear.empty? + ", good morning!" 
  </code></pre>
  
  <p>But the result is an error: undefined method '+' for true</p>
  
  <p>I know the alternative would be to define an additional variable before this statement but I would like to avoid this.</p>