Link a library from other package

[zephyrdaddy]

I am trying to link a library from other ros package to a ros package. I understand that the mrt_cmake_modules should make these entire dependency linkage process smooth and easy, but I am having some trouble linking a library to my package.

I am working on the LIMO SLAM package (link) which rely on the mrt_cmake_modules to generate the dependencies.

In the LIMO SLAM project, different ros packages from other git repos are used and linked.
With the dependencies auto-generated, the launch file can instantiate other package's module. However, what I need is more than this.

I need my main program (also auto-generated through mrt_cmake_modules) to include the headers from other packages. The main program is demo_keyframe_bundle_adjustment_meta/apps/main_program.cpp in my repo. I want it to be able to include the header from an external package called image_preprocessing_tool.

I organized the package structure of the image_preprocessing_tool to be compatible with mrt_cmake_modules guide. I was expecting the mrt_cmake_modules to auto-generate the linkage by putting this package name to my main package, but sadly it does not seem working.

I noticed that the cmake macro MRT_INCLUDE_DIR and the MRT_LIBRARIES seem to be empty which I suppose should contain the paths for the dependent packages. When I added hard coded paths into the cmakelist file, the code worked.

I don't know if I conveyed my problem clearly.

I wasn't sure how to use the mrt_cmake_modules properly for this task.

I would appreciate any help.
Thank you for your help in advance.

[johannes-graeter]

@poggenhans could you help with that, would be greatly appreciated (and repayed in coffee :) )

[johannes-graeter]

@poggenhans ping

[poggenhans]

Well it's a bit hard to figure out whats wrong without any code or minimal example. From the description of your problem my wild guess is that since image_preprocesing_tool is a tool, it doesn't generate a library and thus exports no library targets for CMake. Otherwise your approach sounds correct to me.

Regarding the MRT_LIBRARIES variable and others, it might be that the documentation on this is a bit outdated. I think this variable is no longer used because of the obvious downsides of using a global variable. Instead, an interface library target named <mypackage>::auto_deps is created which in turn depends on all targets specified in package.xml and this is automatically linked when using mrt_add_library or mrt_add_executable.

[zephyrdaddy]

@poggenhans @johannes-graeter Thanks very much for the help! I will do the following.

1. Make a minimal example that represents my need

2. Check the difference btw normal packages and the "tools" packages.

3. Check the interface library target <mypackage>::auto_deps

Thanks a lot!