Assign <#nested> to variable in FreeMarker

FreeMarker is awesome template engine. I'm still wonder how much powerful it is and how flexible it can be when you need. Last week, when I was writing a simple macro to render tweets using user defined template, my though was that it may be good to define this template as macro nested content. For instance:

  <@tweets 'rkhmelyuk', 10>
      [picture] [username]: <br/>
      [message]<br/>
      <a href="[url]">[date]</a>
  </@tweets>

Pretty simple, but the only way for me was to load tweets using Twitter API through JSONP protocol. So my macro was need to generate a javascript code, that should correctly define callback and fetch tweets. Callback function simply applies received JSON data to the user defined template.

And here is the problem. How to get macro's nested content into javascript variable? Well, who ever used FreeMarker knows that nested content can be rendered with command <#nested/>. This could be a solution, but isn't. Why? Because I need to do extra preparing of template to put it as a javascript string. I need to remove newlines and replace quotes. So the best decision is to put nested content as Freemarker variable and do preparation over it first and than insert into javascript. And here is the power of Freemarker. This was possible and easy to do with <#assign/> or <#local/> command:

 <#local layout><#nested/></#local>
 <#-- Now layout variable contains a template defined as nested -->
 <script type="text/javascript">
    function callback_${id}(data) {
       var layout = "${layout?SomePreparationsGoHere}";
       renderTweets(layout, data);
    }
 </script>

In this code, the nested content is assigned to variable layout. Then we generates a javascript code and insert layout variable as string, but first do some preparations.

I also like flexibility of Freemarker. I hope that could find a time and describe some other tips about it soon.