feat(lifecycle_node): add get_parameter_or overload returning value or alternative

Signed-off-by: Zheng Qu <[email protected]>

Author: Maverobot

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_