How do I dereference a namespace name in my launch file ?

edit

Hi @electrophod

How about using the Group option that provides the XML launch. Like so:

<?xml version="1.0"?>
<launch>

  <arg name="ns0" default="ares"/> <!-- Namespace 0 -->
  <arg name="ns1" default="ares"/> <!-- Namespace 1 -->

  <!-- Group namespace 0 Nodes -->
  <group ns="$(arg ns0)">
    <!-- Include nodes that works in namespace 0 -->
    <include...>
    ...
    </include>
  </group>

  <!-- Include nodes that works in global namespace -->
  <include...>
  ...
  </include>

  <!-- Group namespace 1 Nodes -->
  <group ns="$(arg ns1)">
    <!-- Include nodes that works in namespace 1 -->
    <include...>
    ...
    </include>
  </group>

</launch>

And call it like this:

roslaunch package my_launch.launch ns0:=namespace_0 ns1:=namespace_1

I do not know if that is exactly what you want, if it not the case I will update the answer.