Help find catkin python for install underlays

[stonier]

This is a follow on from #397

[stonier]

This is safe - side effects such as taking care of environment variables like ROS_PACKAGE_PATH and ROS_ROOT are not handled by this script. That is done by devel/env.sh and this script just computes the difference between environments. See the discussion in #397.

[dirk-thomas]

If I understand the discussion right (sorry, has been a while) you extend the sys path to be able to find the following catkin.* imports. It is only relavant if the PYTHONPATH was not set before invoking it and it is not used to find python stuff from other packages, right?

If that is true, I would recommend we update the condition in line 8 to not look for a file "catkinConfig.cmake.in" (which does not get installed) but for a different file e.g. "toplevel.cmake" which is there in source and install space.

[stonier]

To the first question, yes - it is just looking for catkin's python path, nothing else.

To the second point - looking for an installed file like toplevel.cmake is moot since catkin's python does not reside at the relative ../python location (in the install space it is in /opt/ros/groovy/lib/python2.7/dist-packages/catkin. ../../../lib/python2.7/dist-packages/catkin is very different to ../python.

Hence the two separate search rules.

Having a look at that commit again, it should probably use an else argument so that it doesn't override the location if found in the source space. It could probably hunt in those workspace python paths specifically for catkin's package before adding it PYTHONPATH and break once it finds one too. That perhaps is just extra code for no valuable reason.

I'll update tonight.

[dirk-thomas]

Oh, I didn't see that. That's why we check for catkinConfig.cmake.in. I can make a patch which uses your loop over the workspaces and adds the one specific folder which contains catkin.

[dirk-thomas]

The following looks clean to me - what do you think?

# find the import relatively if available to work before installing catkin or overlaying installed version
if os.path.exists(os.path.join('@catkin_EXTRAS_DIR@', 'catkinConfig.cmake.in')):
    sys.path.insert(0, os.path.join('@catkin_EXTRAS_DIR@', '..', 'python'))
try:
    from catkin.environment_cache import generate_environment_script
except ImportError:
    # search for catkin package in all workspaces and prepend to path
    for workspace in "@CATKIN_WORKSPACES@".split(';'):
        python_path = os.path.join(workspace, '@CATKIN_GLOBAL_PYTHON_DESTINATION@'))
        if os.path.isdir(os.path.join(python_path, 'catkin'):
            sys.path.insert(0, python_path)
            break
    from catkin.environment_cache import generate_environment_script

[stonier]

Just tested it with a couple of erratic ')' bug fixes:

if os.path.exists(os.path.join('@catkin_EXTRAS_DIR@', 'catkinConfig.cmake.in')):
    sys.path.insert(0, os.path.join('@catkin_EXTRAS_DIR@', '..', 'python'))
try:
    from catkin.environment_cache import generate_environment_script
except ImportError:
    # search for catkin package in all workspaces and prepend to path
    for workspace in "@CATKIN_WORKSPACES@".split(';'):
        python_path = os.path.join(workspace, '@CATKIN_GLOBAL_PYTHON_DESTINATION@')
        if os.path.isdir(os.path.join(python_path, 'catkin')):
            sys.path.insert(0, python_path)
            break
    from catkin.environment_cache import generate_environment_script

Works great.

[stonier]

Updated and rebased the commit.

[dirk-thomas]

Two minor formulation issues:

• "module" -> "package" since there is no module "catkin" - only a package

• "devel space" is not correct, it must be "source space" since the python files are not copied.

  find the import for catkin's python package - either from source space or from an installed underlay

[stonier]

Updated.

[dirk-thomas]

Thank you, for taking the time to push on this.