[ros-users] Nodelet .so dependencies

[Andy Somerville]

On Tue, Dec 14, 2010 at 7:02 PM, Andy Somerville
<andy.somerville at resquared.com> wrote:
> I've been creating a sample project to get myself comfortable with the
> nodelet/pluginlib context lately. In doing so I've come across the
> following problem:
>
> When running my nodelet it fails to start with the an error message
> indicating it's having trouble locating a symbol within one of its
> dependencies:
>
>    /opt/ros/cturtle/stacks/common/nodelet/bin/nodelet: symbol lookup
> error: /home/somervil/Projects/rdk2context/stacks/video_nodelet/lib/libvideonodelet.so:
> undefined symbol:
> _Z20usb_cam_camera_startPKc17usb_cam_io_method20usb_cam_pixel_formatii
>
> and then
>
> I know the following:
>  * My nodelet is dependent on usb_cam which I have listed as a
> dependency in the manifest.
>  * libusb_cam.so is where the offending undefined symbol should live.
>  * libusb_cam.so has been build and exists in usb_cam/lib
>  * usb_cam is in the ROS_PACKAGE_PATH
>  * usb_cam is exporting it's relevant path
>
> It's unclear to me how the nodelet/plugin system would be aware of a
> nodelet's dependencies, and where to look for them, thus explaining
> the problem I'm seeing. But since I haven't seem other people raise
> the issue, I imagine I must be doing something wrong.
>
> The only think I can imagine is that I'm supposed to be passing the
> dependencies to the nodelets manager but in looking in the nodelet
> code, that doesn't seem to be correct.
>
>
>
> TL;DR: Does anyone know how to supply the nodelet manager with the
> info it needs to resolve symbols from dependencies?
>
>
>     Andy Somerville
>

I've found a solution, but I'm wondering if it's the "correct"
solution considering that ros' build system normally handles
dependencies through manifest.xml

Adding the line:

    target_link_libraries(videonodelet usb_cam)

to my CMakeLists.txt causes the libvideonodelet.so library to link in
info for ubs_cam.

Anyone know if this is the preferred way or if there's a more
automatic solution?

     Andy