title: Sane way to concat string and variable in Handlebars.js helper argument?
body: <p>I'm trying to build a simple modal component in Ember, but it seems the "logic-less" of Handlebars is too illogical for me. Is there any sane way to achieve a result somewhat this?</p>
  
  <pre><code>&lt;h2&gt;Nice block about {{title}}&lt;/h2&gt;
  &lt;a href="#" data-toggle="modal" id="add-item-{{title}}"&gt; {{!this works}}
  
  {{#my-modal modal-id="add-item-{{title}}" header='New {{title}}'}} {{! those don't}}
    &lt;p&gt;My body blabla&lt;/p&gt;
  {{/my-modal}}
  </code></pre>
  
  <p>Currently I end up by getting my modal id being <code>"add-item-{{title}}"</code>, literally, as well as the modal title.</p>
  
  <p>And... no, for now I'm not considering passing the "title" as a new param and using it in the modal. The modal header in another template might not be "New {{title}}" but "are you sure?" or "details about <code>{{title}}</code>".</p>