title: PHP: How {{string}} into a php code
body: <p>How do you turn a piece of <code>{{string}}</code> into a php <code>code</code>, for instance,</p>
  
  <pre><code>{{secure_base_url}}
  </code></pre>
  
  <p>to </p>
  
  <pre><code>echo secure_base_url;
  </code></pre>
  
  <p>I see this kind of method is used a lot in Magento. I wonder how do you do it if you are writing your own programme. Do I need some kind of plugin to turn that kind of <code>{{string}}s</code> to <code>codes</code>?</p>