Fix: Ensure parameters are initialized with default values if undefined in params.yml

[nzantopp]

Description:
This merge request resolves the issue where parameters declared in a Python ROS2 node were not being initialized when missing from params.yml. This caused the parameters to be inaccessible in parameter management tools like rqt and unavailable via ros2 param get commands.

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Issue Reference:
Closes #4.

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Changes:

• Modified the parameter declaration logic to ensure parameters are initialized with their default values even when not defined in params.yml.
• Used set_parameters after declaring the parameters to register them correctly.

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Steps to Reproduce:
The issue can be reproduced as follows:

1. Create a ROS2 node with the following parameter declaration:

   self.param2 = 1
   self.param2 = self.declareAndLoadParameter(name="param2",
                                               param_type=rclpy.Parameter.Type.INTEGER,
                                               description="TODO",
                                               default=self.param2,
                                               from_value=0,
                                               to_value=9,
                                               step_value=1)

2. Launch the node without defining param2 in params.yml.
3. Before the fix, no parameters would appear in rqt or via ros2 param get. After the fix, the declared parameter should be initialized and visible.

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Testing:

• Tested locally on ROS2 Humble with Ubuntu 22.04.
• Verified that:
  • Parameters not defined in params.yml are initialized with default values.
  • These parameters appear in rqt.
  • ros2 param commands (e.g., ros2 param get) correctly display the parameters.

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Impact:
This fix does not break existing functionality. Instead, it ensures that declared parameters are initialized properly, even if not defined in external configuration files.

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Screenshots/Logs:
(Optional: Include screenshots or logs demonstrating the fix in action. For example, a screenshot of rqt showing the previously missing parameter.)

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Code Snippet of the Fix:

# Ensure the parameter is explicitly registered if not provided in params.yml
            else:
                self.get_logger().warn(f"Missing parameter '{name}', using default value: {default}")
                param = default
                self.set_parameters([rclpy.Parameter(name=name, value=param)])

[lreiher]

Thank you very much for the extensive issue description and the fix!

I have two small requests:

1. Would you mind also checking if a similar change is required in the C++ template node?
2. Could you please regenerate the samples by simply running generate_samples.sh and then committing the changes?

[nzantopp]

Would you mind also checking if a similar change is required in the C++ template node?

• Similar changes added

Could you please regenerate the samples by simply running generate_samples.sh and then committing the changes?

• Generated and added