Create a ROS2 Python Package

Lets create a new Python Package

Create a ROS2 Package

Use the ROS2 pkg create command to create .

ros2 pkg create my_py_pkg --build-type ament_python --dependencies rclpy

This will create a new folder that includes the dependencies needed for this package (the rclpy library), as well as the files required to install this such as the setup.py file.

The package.xml file is also created. This contains the version, description, maintainer contact details as well as the licence type. It also contains the depednecnies for this package; the rcply library we specified.

Build the new package

Lets build the new package

colcon build

1 package had sdrerr output:

If you get and error message that says:

Summary: 1 package finished [3.60s]
  1 package had stderr output: my_py_pkg

This was because there is a bug in the setuptooldependency package, we can fix this by using a known good version of pip3:

• Install pip3 - from the docker terminal type:

sudo apt update && sudo apt install pip -y

• Downgrade pip - from the docker terminal type:

pip install setuptools==58.2.0

This should fix the error; type colcon build again to successfully build the package.

Fix permissions

We need to fix the permissions to edit files in these folders, from with VSCode:

• Change permisions on the folder - From the docker commandline type:

chmod 777 -R  my_py_pkg/

Add a dependency to our package.xml

• Open the package.xml - In VSCode open the package.xml file within the my_py_pkg folder
• Add the depenecy - add the following text underneath <depend>rclpy</depend>:

<depend>std_msgs</depend>

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