Ask Your Question

Difference Between build_depends and find_package components

asked 2013-10-07 09:26:06 -0500

David Lu gravatar image

What is the difference between listing something as a build_depends and listing it in the find_package macro? It seems redundant.

edit retag flag offensive close merge delete

2 Answers

Sort by ยป oldest newest most voted

answered 2013-10-07 10:12:13 -0500

joq gravatar image

It mostly is redundant.

Some system dependencies declare non-standard CMake variables, so the CMake interface does need to be spelled out explicitly somewhere, and CMakeLists.txt is a reasonable choice.

Because CMake scripts are not easy for other tools to parse, some information is duplicated in package.xml, where it is more-readily accessible.

edit flag offensive delete link more



So you need to take care of both files simultaneously? Not very efficient...

Hendrik Wiese gravatar image Hendrik Wiese  ( 2013-10-07 11:23:25 -0500 )edit

There is also this option: .

joq gravatar image joq  ( 2013-10-07 12:08:55 -0500 )edit

Was that ever advertised?

David Lu gravatar image David Lu  ( 2013-10-07 12:40:06 -0500 )edit

FYI, catkin_simple is very unstable, it might change, without warning, in the future (names, api, etc..). I would recommend forking it if you want to use it. It was never advertised because it isn't finished, it doesn't support actions or dynamic_reconfigure and has almost no documentation.

William gravatar image William  ( 2013-10-07 12:57:46 -0500 )edit

There are also cases when you do not want all the dependencies in the CMakeLists.txt if you have dependencies on non-C style packages which provide potentially other resources or tools not able to be integrated into CMake.

tfoote gravatar image tfoote  ( 2013-10-09 17:32:29 -0500 )edit

answered 2013-10-07 12:55:07 -0500

Dirk Thomas gravatar image

The package.xml files contain rosdep keys for system dependencies as well as ROS package names. Sadly there is simply no 1-to-1 mapping between those and the find_package() names. So any heuristic (like as it is done in catkin_simple) will never work 100% reliable. That is the reason why the developer has to specify them separately.

edit flag offensive delete link more



That is pretty stupid in my book... Unnecessary redundant redundancy. Who could take care of this flaw?

Hendrik Wiese gravatar image Hendrik Wiese  ( 2013-10-07 21:39:48 -0500 )edit

@Hendrik_SeveQ_Wiese `catkin_simple` tries to deal with this, but will fail if a caktin dependency is missing. Basically, for each `build_depend` it calls `find_package(build_depend)` and if it is not found it assumes it is a System package which either doesn't have a CMake Module or doesn't set canonical CMake variables, but it could be that it actually is a catkin package but is not present. There is no way to distinguish between the two cases.

William gravatar image William  ( 2013-10-07 22:30:52 -0500 )edit

How did rosbuild deal with it?

David Lu gravatar image David Lu  ( 2013-10-08 05:11:38 -0500 )edit

It just did not. It gets the pkg-config information for all ROS dependencies. But for non-ROS dependencies the developer has to deal with it manually - just because there is no way to do that in a generic way.

Dirk Thomas gravatar image Dirk Thomas  ( 2013-10-08 07:08:05 -0500 )edit

@David Lu rosbuild differentiated between rosbuild packages and system packages, <depend> vs <rosdep> tags. But the <depend> tags were not used in packaging, so you had to maintain a second, redundant stack level dependency tree when releasing your code.

William gravatar image William  ( 2013-10-08 07:30:53 -0500 )edit

Your Answer

Please start posting anonymously - your entry will be published after you log in or create a new account.

Add Answer

Question Tools



Asked: 2013-10-07 09:26:06 -0500

Seen: 596 times

Last updated: Oct 07 '13