Unit 07 · lesson

`setup.py`, `setup.cfg`, and Entry Points

A Python file existing in your source tree does not automatically make this work:

ros2 run robotnix_pubsub talker

The package must install an executable entry point.

`setup.cfg`

The generated file tells setuptools where package executables should be installed. The official tutorial notes that ros2 run looks for them under the package's lib install location.

Inspect:

cat setup.cfg

`setup.py`

Open setup.py and find:

entry_points={
    'console_scripts': [
    ],
}

Later you will add:

'talker = robotnix_pubsub.talker:main',
'listener = robotnix_pubsub.listener:main',

Read the mapping:

CLI executable name
  = Python module path : function

Metadata consistency

The official tutorial instructs Python packages to keep name/version/maintainer/description/license metadata consistent between package.xml and setup.py where those fields overlap.

Checkpoint

Predict what happens if:

talker.py exists;
the package builds;
but no talker = ...:main entry point is installed.

The likely failure is executable discovery, not topic communication.