init: ROS2 learning suite

src/py_srv/launch/srv_launch.py

@@ -0,0 +1,23 @@
+"""
+srv_launch.py —— 启动 add_two_ints 服务端的 launch 文件。
+
+注意:client 不在这里启动,因它是"一次性调用",通常在终端或脚本里跑。
+client 用法:
+    source install/setup.bash
+    ros2 run py_srv add_two_ints_client 1 2       # 默认参数
+    ros2 service call /add_two_ints example_interfaces/srv/AddTwoInts "{a: 3, b: 5}"
+"""
+
+from launch import LaunchDescription
+from launch_ros.actions import Node
+
+
+def generate_launch_description():
+    return LaunchDescription([
+        Node(
+            package='py_srv',
+            executable='add_two_ints_server',
+            name='add_two_ints_server_py',
+            output='screen',
+        ),
+    ])