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2015-07-01 15:41:42 -0500 marked best answer Unbound prefix error in xarco file

I am getting an unbound prefix error when I try to use an xarco macro. I do have the xmlns:xarco defined however. This is my xarco file:

<?xml version="1.0"?>
<robot xmlns:xacro="[link to xarco wiki]" name="flexible">
  <xacro:macro name="test_macro" >
    <test name="x"/>


And this is the error I am getting:

Expat parsing error.  Check that:
 - Your XML is correctly formed
 - You have the xacro xmlns declaration: xmlns:xacro="[link to xarco wiki]"

Traceback (most recent call last):
  File "/opt/ros/hydro/share/xacro/", line 60, in <module>
  File "/opt/ros/hydro/lib/python2.7/dist-packages/xacro/", line 571, in main
    doc = parse(f)
  File "/usr/lib/python2.7/xml/dom/", line 1920, in parse
    return expatbuilder.parse(file)
  File "/usr/lib/python2.7/xml/dom/", line 928, in parse
    result = builder.parseFile(file)
  File "/usr/lib/python2.7/xml/dom/", line 207, in parseFile
    parser.Parse(buffer, 0)
xml.parsers.expat.ExpatError: unbound prefix: line 7, column 6

Any help would be appreciated.

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2014-01-28 17:31:40 -0500 marked best answer Why does catkin add the src directory of the workspace to ROS_PACKAGE_PATH and not the devel directory?

If the devel space is supposed to mimic the install space, (as described in, should that not be what is added to the ROS_PACKAGE_PATH? It seems confusing to have the package.xml and .launch files remain in the src directory and the binary targets copied to the devel directory...

2014-01-28 17:31:39 -0500 marked best answer When to call generate_message() in CMakeLists.txt

Do I need to call generate_message() when I am only using a message defined in another package, and not defining one in my package?

It seems like I should not, since the code for the messages are already generated in the package defining it, which I am including. But the tutorial "Writing a Simple Publisher and Subscriber (C++)" has a call to generate_message() even though it only uses the std_msgs/String message, and does not define any of its own.

Can someone clarify the situation?

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2013-09-28 06:58:49 -0500 commented answer Old versions of packages in ROS repository

Ok, thank you. I guess I will just compile from source in github.

2013-09-27 08:24:54 -0500 asked a question Old versions of packages in ROS repository

The latest version of the ros-hydro-gazebo-plugins package (2.3.2-0precise-20130920-2002-+0000) is broken (this bug) and I want to downgrade it to the previous version. The ROS repository however seems to have only the latest version of the package. Where can I get older versions?

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2013-09-15 06:51:51 -0500 commented answer How do I use PCL from ROS Hydro?

Can specify exactly what error you are getting? And are you using ROS Hydro?

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2013-09-12 08:17:39 -0500 answered a question How do I use PCL from ROS Hydro?

The question was answered in the PCL Users mailing list.

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2013-09-11 18:01:41 -0500 asked a question How do I use PCL from ROS Hydro?

I am trying to understand how PCL is integrated into ROS Hydro. I installed ROS in Ubuntu 12.04 using the ros-hydro-desktop-full package. From "rospack list" I can see that it comes with 4 PCL packages:

  1. pcl
  2. pcl_conversions
  3. pcl_msgs
  4. pcl_ros

What is the functionality of these 4 packages, especially pcl_ros and pcl? There is also a pcl-1.7 folder in my /opt/ros/hydro/share folder with some cmake config files. There is no package.xml file though. What does this folder do?

Also, I seem to have 2 copies of the pcl-1.7 libraries. I have it in /usr/lib and also in /opt/ros/hydro/lib. So it seems like I have a standalone pcl library (I am not sure how I got this) and one that is integrated with ROS. Is this going to be a problem?

Finally, and this is the biggest source of my confusion, the wiki page for hydro/migration says:

pcl is no longer packaged by the ROS community as a catkin package, so any packages which directly depend on pcl should instead use the new rosdep rules libpcl-all and libpcl-all-dev and follow the PCL developer's guidelines for using PCL in your CMake.

So, why is there a pcl package in ROS Hydro in the first place with libraries in /opt/ros/hydro/lib?

As you can see I am quite confused, any help will be greatly appreciated!