dz_launch_examples

Some examples of ROS 2 launch files in Python, XML, and YAML.

Argument declaration examples

The launch files arg_examples.launch.py, arg_examples.launch.xml, and arg_examples.launch.yaml show off some features of argument declaration.

These were developed to try to understand ros2/launch#698

They simply declare and print a set of arguments.

Run (with .py, .xml, or, yaml in place of <extension>):

ros2 launch dz_launch_examples arg_examples.launch.<extension> simple_arg:=<some value>

The Python version also demonstrates:

• Iteration over a launch context's configuration to get the names and values of declared launch arguments
• Use of launch.actions.LogInfo to log information from the log file.

To see the declared arguments and their descriptions and valid choices, run:

ros2 launch dz_launch_examples arg_examples.launch.<extension> --show-args

Node preparation in Python OpaqueFunction

This provides an example of returning several talker/listener node pairs in consecutively numbered namespaces, inspired by this post.

To launch three node pairs, for example, run:

ros2 launch dz_launch_examples opaque_multi_nodes.launch.py num_node_pairs:=3