Add get_parameter_or overload returning value or alternative

rclcpp_lifecycle/include/rclcpp_lifecycle/lifecycle_node.hpp

@@ -486,6 +486,16 @@ class LifecycleNode : public node_interfaces::LifecycleNodeInterface,
     ParameterT & value,
     const ParameterT & alternative_value) const;
 
+  /// Return the parameter value, or the "alternative_value" if not set.
+  /**
+   * \sa rclcpp::Node::get_parameter_or
+   */
+  template<typename ParameterT>
+  ParameterT
+  get_parameter_or(
+    const std::string & name,
+    const ParameterT & alternative_value) const;
+
   /// Return the parameters by the given parameter names.
   /**
    * \sa rclcpp::Node::get_parameters

rclcpp_lifecycle/include/rclcpp_lifecycle/lifecycle_node_impl.hpp

@@ -306,5 +306,16 @@ LifecycleNode::get_parameter_or(
   return got_parameter;
 }
 
+template<typename ParameterT>
+ParameterT
+LifecycleNode::get_parameter_or(
+  const std::string & name,
+  const ParameterT & alternative_value) const
+{
+  ParameterT parameter;
+  get_parameter_or(name, parameter, alternative_value);
+  return parameter;
+}
+
 }  // namespace rclcpp_lifecycle
 #endif  // RCLCPP_LIFECYCLE__LIFECYCLE_NODE_IMPL_HPP_

rclcpp_lifecycle/test/test_lifecycle_node.cpp

@@ -840,6 +840,26 @@ TEST_F(TestDefaultStateMachine, check_parameters) {
   EXPECT_TRUE(parameter.as_bool());
 }
 
+TEST_F(TestDefaultStateMachine, test_get_parameter_or) {
+  auto test_node = std::make_shared<EmptyLifecycleNode>("testnode");
+
+  const std::string param_name = "test_param";
+  int param_int = -999;
+
+  // Parameter does not exist, should return "or" value
+  EXPECT_FALSE(test_node->get_parameter_or(param_name, param_int, 123));
+  EXPECT_EQ(param_int, 123);
+  EXPECT_EQ(test_node->get_parameter_or(param_name, 456), 456);
+
+  // Declare param_int
+  test_node->declare_parameter(param_name, rclcpp::ParameterValue(789));
+
+  // Parameter exists, should return existing value
+  EXPECT_TRUE(test_node->get_parameter_or(param_name, param_int, 123));
+  EXPECT_EQ(param_int, 789);
+  EXPECT_EQ(test_node->get_parameter_or(param_name, 456), 789);
+}
+
 TEST_F(TestDefaultStateMachine, test_getters) {
   auto test_node = std::make_shared<EmptyLifecycleNode>("testnode");
   auto options = test_node->get_node_options();