better_launch

A better replacement for the ROS2 launch system: intuitive, simple, memorable.

README

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[!TIP] Just looking for the documentation? We also have various examples!

🧭 About

Let’s face it: ROS2 has been a severe downgrade in terms of usability compared to ROS1. While there are many considerable improvements, the current launch system is borderline unusable.

better_launch is what I wish ROS2 launch would be: intuitive to use, simple to understand, easy to remember. This is why better_launch is not yet another abstraction layer over ROS2 launch; it is a full replacement with no required dependencies on the existing launch system.

Instead of dozens of imports and class instances for even the most basic tasks, your launchfiles could look as simple and beautiful as this:

from better_launch import BetterLaunch, launch_this

@launch_this
def my_main(enable_x: bool = True):
    """This is how nice your launchfiles could be!
    """
    bl = BetterLaunch()

    if enable_x:
        bl.node(
            "examples_rclpy_minimal_publisher",
            "publisher_local_function",
            "example_publisher",
        )

    # Include other launchfiles, even regular ROS2 launchfiles!
    bl.include("better_launch", "ros2_turtlesim.launch.py")

# You can use `ros2 launch`, too, but `bl` is better :)
$> bl my_package my_launch_file.py --enable_x True

Do I have your attention? Read on to learn more!

🧞‍♀️ Everything you need to know

⛲ Highlights

📟 The TUI

[!NOTE] Using the TUI

better_launch comes with an optional, unobstrusive TUI (terminal user interface) based on prompt_toolkit, which will hover below the log output.

TUI

See the single line of shortcuts at the bottom? That’s the TUI, and it will never take up more than 3 lines! Despite its simplicity, the TUI allows you a comfortable degree of control over all nodes managed by the better_launch process it is running in:

listing a node’s services and topics
starting and stopping nodes
triggering lifecycle transitions
changing the log level
etc.

# Run this line to see it in action!
bl better_launch 02_ui.launch.py

⛱️ TOML launchfiles

[!NOTE] Specification

For those with aversions against using a turing-complete programming language to specify system startup - fear not! better_launch introduces a new launchfile format based on TOML.

enable = true

[a_simple_cube]
if = "${enable}"
func = "find"
package = "better_launch"
filename = "cube.sdf"

[print_me_baby]
func = "log"
severity = "info"
message = "Found cube at ${a_simple_cube}"

Under the hood, TOML launchfiles result in calls to the BetterLaunch singleton, but offer a more focused and constrained feature set. If you are still missing ROS1 XML launchfiles (and substitutions like ${arg my_arg}!), these are for you!

🌱 Contributions

[!IMPORTANT] Please see this document if you’re planning to make PR!

Author: Nikolas Dahn

Testing & Feedback:

better_launch was initiated and is currently developed at the Robotics Innovation Center of the German Research Center for Artificial Intelligence (DFKI) in Bremen.

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