title: Ruby concatenate strings and add spaces
body: <p>I have 4 string variables <code>name, quest, favorite_color, speed</code> that might be empty.  I want to concatenate them all together, putting spaces between those that aren't empty.  Simplicity of the code, i.e how simple is to to look at and understand, is more important than speed.</p>
  
  <p>So:</p>
  
  <pre><code>name = 'Tim'
  quest = 'destroy'
  favorite_color = 'red'
  speed = 'fast'
  </code></pre>
  
  <p>becomes</p>
  
  <pre><code>'Tim destroy red fast'
  </code></pre>
  
  <p>and</p>
  
  <pre><code>name = 'Steve'
  quest = ''
  favorite_color = ''
  speed = 'slow'
  </code></pre>
  
  <p>becomes:</p>
  
  <pre><code>'Steve slow'
  </code></pre>
  
  <p>Note there is only 1 space between 'Steve' and 'slow'.</p>
  
  <p>How do I do that (preferably in 1 line)?  </p>