[ros-users] Python version of rospack

Mike Purvis mpurvis at clearpathrobotics.com
Thu Mar 3 15:55:45 UTC 2011


I'm doing a bit of experimenting with getting ros_comm running on an
embedded Linux platform. For the moment, I'm ignoring roscpp (and the
roscpp-based eros project), and just concentrating on a rospy-based client,
since the platform already has a working Python 2.6 environment with expat
and yaml. This is similar work to what has been done to get rospy running on
Android devices: http://www.ros.org/wiki/android.

It seems to be basically working. The one major frustration at this point
stems from rospack being a compiled utility. Has there been any work (or
desire) to port this program to Python? I note that in roslib/packages.py,
there's a note to move the get_pkg_dir function to something not based on
rospack---would there be the possibility of them both deriving from common
library code? The ROS-android project would benefit from this as
well---manifests are currently unsupported there, possibly for this reason?

What I've done so far to get it up at all is dump the packages and stacks I
need into the root directory, and then implement a trivial stub rospack,
like so:

#!/usr/bin/env python

import sys, os

cmd = sys.argv[1]

if cmd == 'find':
  paths = ["/root/", "/root/messages/", "/root/common_msgs/",
  pkg = sys.argv[2]

  for path in paths:
    if os.path.exists(path + pkg):
      print(path + pkg)

Doesn't look like much, but with manual dependency resolution and running of
genmsg_py.py, that's enough to launch a rospy node which communicates to an
offboard roscore.

Any thoughts?



*Mike Purvis* | Software Architect | Clearpath Robotics, Inc.

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