Can we stack catkin venv workspaces ? about catkin_virtualenv

[paulbovbel]

catkin_virtualenv doesn't under/overlay the virtualenvs themselves - each package cmakelists generates a virtualenv containing all python requirements from the entire dependency tree.

So the current implementation is definitely bulky. I tried to avoid getting too deep into python internals, and used the considerably better tested dh_virtualenv as a base for making the package's virtualenv 'relocatable'.

The approach here is sort of orthogonal to catkin_pip - I was motivated primarily to enable pip dependency management (and as a bonus python3) for ros_buildfarm users, and make it transparent with standard tools like roslaunch/rosrun/rostest. I'd welcome any advice on how to do things cleaner - I have a fairly shallow grasp on python internals at this level.

[paulbovbel]

Going to close this as an issue, but I'd be happy to discuss any architecture ideas further