Revert "Fix python lib install path (#207)"

[sea-bass]

This reverts commit 4e92cc4.

Turns out I took #207 in good faith, but it does cause problems.

Without that PR, this is what a custom module named admittance_params.py installs into. This is correct:

With that PR, it goes to the wrong folder one level up:

[sea-bass]

@agonzat FYI, I think this change needs to be reverted. If you have any information on the motivation behind your original PR (#207), please let us know!

[christophfroehlich]

LGTM, because it seems there were less issues before the change

[MarqRazz]

I just checked with my external package that uses generate_param and the generate python file is still being placed in the directory install/my_package/lib/python3.10/site-packages/my_package/generated_parameter_file.py, but running my test with colcon test still fail to import it.

To test this out I purged the binary install and checked out this branch and rebuilt with colcon build.

[sea-bass]

Weird. Did you also rebuild the generate_parameter_library packages?

[MarqRazz]

Weird. Did you also rebuild the generate_parameter_library packages?

Yes I did. Sorry I corrected my post. It looks like that is the directory you are expecting this PR to place the files into but running test still fail so I'm not sure if you expected this to fix it being found when running colcon test.

[sea-bass]

running test still fail so I'm not sure if you expected this to fix it being found when running colcon test.

Right, this one just reverts the install path to fix it. But the tests should still fail.

The tests will pass if you try with #237... AND you remove the __init__.py from your custom params package's source folder.

[MarqRazz]

Also, the colcon test will fail unless you try with #237...

AND you remove the __init__.py from your custom params package's source folder

Sorry I missed that second PR. Yes running with #237 and removing __init__.py from my custom parameters package does fix the test! Thanks for the help @sea-bass!

[imcelroy]

@sea-bass I'm not sure this was problematic. The unit tests do run correctly now, but I get errors when I build using --merge-install and try running the test_node after these changes.

Steps to reproduce:

1. colcon build --merge-install
2. source install/setup.bash
3. ros2 run generate_parameter_module_example test_node

Traceback (most recent call last):
  File "/home/user/test_ws/install/lib/generate_parameter_module_example/test_node", line 33, in <module>
    sys.exit(load_entry_point('generate-parameter-module-example==0.4.0', 'console_scripts', 'test_node')())
  File "/home/user/test_ws/install/lib/generate_parameter_module_example/test_node", line 25, in importlib_load_entry_point
    return next(matches).load()
  File "/usr/lib/python3.10/importlib/metadata/__init__.py", line 171, in load
    module = import_module(match.group('module'))
  File "/usr/lib/python3.10/importlib/__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1050, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1027, in _find_and_load
  File "<frozen importlib._bootstrap>", line 1004, in _find_and_load_unlocked
ModuleNotFoundError: No module named 'generate_parameter_module_example.minimal_publisher'
[ros2run]: Process exited with failure 1

Here's my PYTHONPATH in order:

• [1] /home/user/test_ws/install/generate_parameter_module_example/lib/python3.10/site-packages
• [2] /home/user/test_ws/install/local/lib/python3.10/dist-packages
• [3] /home/user/test_ws/install/lib/python3.10/site-packages
• [4] /opt/ros/humble/lib/python3.10/site-packages
• [5] /opt/ros/humble/local/lib/python3.10/dist-packages

Here's my file structure:
build/
├── generate_parameter_module_example
│   ├── build
│   │   └── lib
│   │   └── generate_parameter_module_example
│   │   ├── custom_validation.py
│   │   └── minimal_publisher.py <------ no init.py in this folder, therefore not visible to Python ?
│   ├── colcon_build.rc
│   ├── colcon_command_prefix_setup_py.sh
│   ├── colcon_command_prefix_setup_py.sh.env
│   ├── generate_parameter_module_example
│   │   ├── admittance_parameters.py <------ Here there is an init.py, so it can be found, but not in python path
│   │   └── init.py

install/
├── generate_parameter_module_example
│   └── lib
│   │ └── python3.10
│   │ │ └── site-packages <------ [1] /!\ Fails here because it doesn't find minimal_publisher.py, only param module
│   │ │ │ └── generate_parameter_module_example
│   │ │ │ │ ├── admittance_parameters.py
│   │ │ │ │ ├── init.py
├── lib
│   ├── generate_parameter_module_example
│   │   └── test_node
│   └── python3.10
│   │  └── site-packages <------ [3] missing init.py and parameter module
│   │ │  ├── generate_parameter_module_example
│   │   │  │   ├── custom_validation.py
│   │   │  │   ├── minimal_publisher.py
├── local
│   └── lib
│   └── python3.10
│   └── dist-packages
│   ├── cmake_generate_parameter_module_example <------ [2] this has everything, but wrong package
│   │   ├── admittance_parameters.py
│   │   ├── custom_validation.py
│   │   ├── init.py
│   │   ├── minimal_publisher.py
│   │   ├── parameters.yaml