Have node_helpers more closely follow the template

pkgs/node_helpers/node_helpers/nodes/__init__.py

@@ -6,9 +6,11 @@
     TransformsFile,
 )
 from .sound_player import SoundPlayer
+from .node_helpers_node import ExampleNode
 
 __all__ = [
     "HelpfulNode",
+    "ExampleNode",
     "InteractiveTransformPublisher",
     "TransformModel",
     "TransformsFile",

pkgs/node_helpers/node_helpers/nodes/node_helpers_node.py

@@ -0,0 +1,65 @@
+"""This is a total example node to show off some simple node_helpers features. It's not
+meant to be a comprehensive example, but rather a simple one to show off some of the
+features of the node_helpers package.
+"""
+
+from typing import Any
+
+from sensor_msgs.msg import JointState
+
+from node_helpers.nodes import HelpfulNode
+from pydantic import BaseModel
+from node_helpers.spinning import create_spin_function
+from rclpy.qos import qos_profile_services_default
+
+from node_helpers.example_urdf import ForkliftURDF
+
+class ExampleNode(HelpfulNode):
+
+    class Parameters(BaseModel):
+        # Define your ROS parameters here
+        forklift_speed: float  # m/s
+        forklift_max_extent: float
+
+    def __init__(self, **kwargs: Any):
+        super().__init__("ExampleNode", **kwargs)
+        # Load parameters from the ROS parameter server
+        self.params = self.declare_from_pydantic_model(self.Parameters, "root_config")
+        self.urdf = ForkliftURDF.with_namespace(self.get_namespace())
+
+        # Track the forks position and direction, so we can move them up and down
+        self.forklift_position = 0.0
+        self.forklift_direction = 1
+
+        # Create publishers
+        self.joint_state_publisher = self.create_publisher(
+            JointState,
+            "desired_joint_states",
+            qos_profile_services_default
+        )
+
+        # Create a timer to publish joint values
+        self._publish_hz = 20
+        self.create_timer(1 / self._publish_hz, self.on_publish_joints)
+
+
+    def on_publish_joints(self) -> None:
+        if self.forklift_position >= self.params.forklift_max_extent:
+            self.forklift_direction = -1
+        elif self.forklift_position <= 0:
+            self.forklift_direction = 1
+
+        self.forklift_position += self.forklift_direction * self.params.forklift_speed / self._publish_hz
+
+        joint_positions = {
+            self.urdf.joints.FORKS: self.forklift_position
+        }
+
+        self.joint_state_publisher.publish(
+            JointState(
+                name=list(joint_positions.keys()),
+                position = list(joint_positions.values())
+            )
+        )
+
+main = create_spin_function(ExampleNode)

pkgs/node_helpers/pyproject.toml

@@ -19,6 +19,7 @@ transforms3d = "^0.4.2"
 interactive_transform_publisher = "node_helpers.nodes.interactive_transform_publisher:main"
 sound_player = "node_helpers.nodes.sound_player:main"
 placeholder = "node_helpers.nodes.placeholder:main"
+run_ExampleNode = "node_helpers.nodes.node_helpers_node:main"
 
 [tool.colcon-poetry-ros.data-files]
 "share/ament_index/resource_index/packages" = ["resource/node_helpers"]