Calling a function using a variable name

I'd like to call a function based on the value of a variable:

At the moment I have this:

       <o:choose>
	<o:when test="$module='blog'">
	  <!-- Display weblog entries -->
	  <o:eval select="p:blog_default($parameters)" />
	</o:when>
	.
	.
	.
       </o:choose>

But what I would like to do is something like this:

	<o:call-function name="$module"  param=,"$parameters" />

Is this possible in o-xml?

Thanks,
Glen