Dynamically Set Mako Template to Include Another Template

Question

I have a large-ish set of messages, specific to a single page, of which I might night to show any combination of. To simplify adding new messages (the large number is going to get even larger in the short term), and to prevent having a giant if/elif block with an entry for each one, I wanted a way to include all of the relevant templates without having to update the template everytime a new message was added. My though was for dict representing the message to include it's template. This was my attempt at doing so:

<div class="item-content" id="results_content">
  <ul class="unstyled">
     %for msg in c.page_messages:
       <%include file="${msg.get('template_path')}" args="message=msg"/>
     %endfor
  </ul>
</div>

This produces an error at the %include tag:

TypeError: 'NoneType' object has no attribute '__getitem__'

1. Can it be confirmed whether or not I can use a template variable an include tag, I can't seem to find anything specifically stating either way if I should expect this to work.
2. If this is not something that will work, is there another way that I can accomplish the same thing? ie - A new message can be added, without having to modify this template code that pulls in each messages template.

Answer 1

It looks like you can use variables within the include tag in the manner you describe. From the docs:

All tags have a set of attributes which are defined for each tag. Some of these attributes
are required. Also, many attributes support evaluation, meaning you can embed an     
expression (using ${}) inside the attribute text:

<%include file="/foo/bar/${myfile}.txt"/>

My guess is that c.page_messages isn't an iterable of dictionaries at this point.