Add timer demo

Signed-off-by: Michael X. Grey <[email protected]>

Author: mxgrey

examples/logging_demo/Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 name = "logging_demo"
 version = "0.1.0"
-edition = "2024"
+edition = "2021"
 
 [dependencies]
 rclrs = "0.4"

examples/logging_demo/package.xml

@@ -3,7 +3,7 @@
    href="http://download.ros.org/schema/package_format3.xsd"
    schematypens="http://www.w3.org/2001/XMLSchema"?>
 <package format="3">
-  <name>examples_worker_demo</name>
+  <name>examples_logging_demo</name>
   <maintainer email="[email protected]">Esteve Fernandez</maintainer>
   <!-- This project is not military-sponsored, Jacob's employment contract just requires him to use this email address -->
   <maintainer email="[email protected]">Jacob Hassold</maintainer>

examples/timer_demo/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "timer_demo"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+rclrs = "0.4"
+example_interfaces = "*"

examples/timer_demo/package.xml

@@ -0,0 +1,21 @@
+<?xml version="1.0"?>
+<?xml-model
+   href="http://download.ros.org/schema/package_format3.xsd"
+   schematypens="http://www.w3.org/2001/XMLSchema"?>
+<package format="3">
+  <name>examples_timer_demo</name>
+  <maintainer email="[email protected]">Esteve Fernandez</maintainer>
+  <!-- This project is not military-sponsored, Jacob's employment contract just requires him to use this email address -->
+  <maintainer email="[email protected]">Jacob Hassold</maintainer>
+  <version>0.4.1</version>
+  <description>Package containing an example of how to use a worker in rclrs.</description>
+  <license>Apache License 2.0</license>
+
+  <depend>rclrs</depend>
+  <depend>rosidl_runtime_rs</depend>
+  <depend>example_interfaces</depend>
+
+  <export>
+    <build_type>ament_cargo</build_type>
+  </export>
+</package>

examples/timer_demo/src/main.rs

@@ -0,0 +1,26 @@
+/// Creates a SimpleTimerNode, initializes a node and the timer with a callback
+/// that prints the timer callback execution iteration. The callback is executed
+/// thanks to the spin, which is in charge of executing the timer's events among
+/// other entities' events.
+use rclrs::*;
+use std::time::Duration;
+
+fn main() -> Result<(), RclrsError> {
+    let mut executor = Context::default_from_env()?.create_basic_executor();
+    let node = executor.create_node("timer_demo")?;
+    let worker = node.create_worker::<usize>(0);
+    let timer_period = Duration::from_secs(1);
+    let _timer = worker.create_timer_repeating(
+        timer_period,
+        move |count: &mut usize| {
+            *count += 1;
+            println!(
+                "Drinking 🧉 for the {}th time every {:?}.",
+                *count,
+                timer_period,
+            );
+        }
+    )?;
+
+    executor.spin(SpinOptions::default()).first_error()
+}