title: Proper way to concatenate variable strings
body: <p>I need to create new variable from contents of other variables. Currently I'm using something like this:</p>
  
  <pre><code>- command: echo "{{ var1 }}-{{ var2 }}-{{ var3 }}"
    register: newvar
  </code></pre>
  
  <p>The problem is:</p>
  
  <ul>
  <li>Usage of <code>{{ var1 }}...{{ varN }}</code> brings too long strings and very ugly code.</li>
  <li>Usage of <code>{{ newvar.stdout }}</code> a bit better but confusing.</li>
  <li>Usage of <code>set_fact</code> module caches <em>fact</em> between runs. It isn't appropriate for me.</li>
  </ul>
  
  <p>Is there any other solution?</p>