On Thu, May 27, 2010 at 8:25 PM, Mike Purvis
<mpurvis@clearpathrobotics.com>wrote:

> As a new user of ROS, I'm finding it a bit overwhelming trying to know how
> to use the gps_common message that's been proposed above. I've cloned
> umd-ros-pkg, and I've found the gps_common package in the gps_umd stack...
> but there's also the two relevant messages separately appearing in the gpsd
> stack, independent of the gps_common packaging.
>

Those messages in the gpsd stack are an older version of the messages that
appear in gps_umd/gps_common. I'm going to switch gpsd_client over to the
new message format soon (gps_common/[...]), and after that's standardized,
gpsd_client will implement the standard message.


> Should I just be copying the two files from msg to my own project/msg
> directory, or should I be trying to place the gps_common package in some
> centrally-located area, and creating a dependency on it? (How?)
>

It's best to create a dependency on the package. In your manifest.xml:

<package> [...] <depend package="gps_common"/> [...] </package>

I'm not sure what's the best approach for adding repositories right now, but
if you add an entry '/path/to/umd-ros-pkg' to your ROS_PACKAGE_PATH
variable, ROS will be able to find these packages (once you open a new
terminal or otherwise reload ROS). If you installed from source, this
variable is probably set in ~/ros/setup.sh.

Once "roscd gps_common" works and you've built the gps_common package, you
can use GPSFix and GPSStatus in your C++ code:

#include <gps_common/GPSFix.h>
#include <gps_common/GPSStatus.h>

using namespace gps_common;

and these messages will be available as GPSFix and GPSStatus.

 - Ken