From eb4c19d9edb846a3ad31b932b78339115cae52ce Mon Sep 17 00:00:00 2001
From: Sai Kishor Kothakota <sai.kishor@pal-robotics.com>
Date: Wed, 11 Sep 2024 20:07:29 +0200
Subject: [PATCH] [Controller Interface] Make assign and release interfaces
 virtual (#1743)

---
 .../controller_interface_base.hpp               | 17 +++++++++++++++--
 doc/release_notes.rst                           |  1 +
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/controller_interface/include/controller_interface/controller_interface_base.hpp b/controller_interface/include/controller_interface/controller_interface_base.hpp
index fbb2111cc9..c4a19fd8e3 100644
--- a/controller_interface/include/controller_interface/controller_interface_base.hpp
+++ b/controller_interface/include/controller_interface/controller_interface_base.hpp
@@ -104,13 +104,26 @@ class ControllerInterfaceBase : public rclcpp_lifecycle::node_interfaces::Lifecy
   CONTROLLER_INTERFACE_PUBLIC
   virtual InterfaceConfiguration state_interface_configuration() const = 0;
 
+  /// Method that assigns the Loaned interfaces to the controller.
+  /**
+   * Method used by the controller_manager to assign the interfaces to the controller.
+   * \note When this method is overridden, the user has to also implement the `release_interfaces`
+   * method by overriding it to release the interfaces.
+   *
+   * \param[in] command_interfaces vector of command interfaces to be assigned to the controller.
+   * \param[in] state_interfaces vector of state interfaces to be assigned to the controller.
+   */
   CONTROLLER_INTERFACE_PUBLIC
-  void assign_interfaces(
+  virtual void assign_interfaces(
     std::vector<hardware_interface::LoanedCommandInterface> && command_interfaces,
     std::vector<hardware_interface::LoanedStateInterface> && state_interfaces);
 
+  /// Method that releases the Loaned interfaces from the controller.
+  /**
+   * Method used by the controller_manager to release the interfaces from the controller.
+   */
   CONTROLLER_INTERFACE_PUBLIC
-  void release_interfaces();
+  virtual void release_interfaces();
 
   CONTROLLER_INTERFACE_PUBLIC
   return_type init(
diff --git a/doc/release_notes.rst b/doc/release_notes.rst
index bb9c10abe0..b116f78938 100644
--- a/doc/release_notes.rst
+++ b/doc/release_notes.rst
@@ -24,6 +24,7 @@ For details see the controller_manager section.
 * All chainable controllers must implement the method ``export_state_interfaces`` to export the state interfaces, similar to ``export_reference_interfaces`` method that is exporting the reference interfaces.
 * The controllers will now set ``use_global_arguments`` from `NodeOptions <https://docs.ros.org/en/rolling/p/rclcpp/generated/classrclcpp_1_1NodeOptions.html#_CPPv4N6rclcpp11NodeOptions20use_global_argumentsEb>`__ to false, to avoid getting influenced by global arguments (Issue : `#1684 <https://github.com/ros-controls/ros2_control/issues/1684>`_) (`#1694 <https://github.com/ros-controls/ros2_control/pull/1694>`_). From now on, in order to set the parameters to the controller, the ``--param-file`` option from spawner should be used.
 * With (`#1683 <https://github.com/ros-controls/ros2_control/pull/1683>`_) the ``rclcpp_lifecycle::State & get_state()`` and ``void set_state(const rclcpp_lifecycle::State & new_state)`` are replaced by ``rclcpp_lifecycle::State & get_lifecycle_state()`` and ``void set_lifecycle_state(const rclcpp_lifecycle::State & new_state)``. This change affects controllers and hardware. This is related to (`#1240 <https://github.com/ros-controls/ros2_control/pull/1240>`_) as variant support introduces ``get_state`` and ``set_state`` methods for setting/getting state of handles.
+* The ``assign_interfaces`` and ``release_interfaces`` methods are now virtual, so that the user can override them to store the interfaces into custom variable types, so that the user can have the flexibility to take the ownership of the loaned interfaces to the controller (`#1743 <https://github.com/ros-controls/ros2_control/pull/1743>`_)
 
 controller_manager
 ******************