[ros-users] Using ROS from the outside

[Brian Gerkey]

In response to recent conversations with various community members, a
few of us have put together some examples of working with ROS "from
the outside," treating it as you would any software dependency:

https://github.com/gerkey/ros1_external_use

The idea is that, while we use things like catkin and package.xml
files to *develop* ROS, there's no requirement that you also use those
things when you're *using* ROS. You can instead use plain CMake or
even just make (from which you can port to just about anything else)
to find and use software provided by ROS.

So far, we've done examples of: building nodes; doing code generation
for messages, services, and actions; linking out to external libraries
like OpenCV; and installing in a manner that supports tools like
roslaunch. Some examples are rough around the edges, but they should
all work.

Interestingly, there's nothing new here. We're just demonstrating a
work flow that's always been possible but hasn't been well advertised.

Comments, feedback, and improvements (especially ideas for shortening
any of the configuration steps or build files!) are most welcome via
the issue tracker at the repo.

brian.