Separate declare and get params

generate_parameter_library_py/generate_parameter_library_py/jinja_templates/cpp/parameter_library_header

@@ -91,45 +91,57 @@ struct StackParams {
   class ParamListener{
   public:
     // throws rclcpp::exceptions::InvalidParameterValueException on initialization if invalid parameter are loaded
-    ParamListener(rclcpp::Node::SharedPtr node, std::string const& prefix = "")
-    : ParamListener(node->get_node_parameters_interface(), node->get_logger(), prefix) {}
+    ParamListener(rclcpp::Node::SharedPtr node, std::string const& prefix = "", bool initialize_params = true)
+    : ParamListener(node->get_node_parameters_interface(), node->get_logger(), prefix, initialize_params) {}
 
-    ParamListener(rclcpp_lifecycle::LifecycleNode::SharedPtr node, std::string const& prefix = "")
-    : ParamListener(node->get_node_parameters_interface(), node->get_logger(), prefix) {}
+    ParamListener(rclcpp_lifecycle::LifecycleNode::SharedPtr node, std::string const& prefix = "", bool initialize_params = true)
+    : ParamListener(node->get_node_parameters_interface(), node->get_logger(), prefix, initialize_params) {}
 
     ParamListener(const std::shared_ptr<rclcpp::node_interfaces::NodeParametersInterface>& parameters_interface,
-                  std::string const& prefix = "")
-    : ParamListener(parameters_interface, rclcpp::get_logger("{{namespace}}"), prefix) {
+                  std::string const& prefix = "", bool initialize_params = true)
+    : ParamListener(parameters_interface, rclcpp::get_logger("{{namespace}}"), prefix, initialize_params) {
       RCLCPP_DEBUG(logger_, "ParameterListener: Not using node logger, recommend using other constructors to use a node logger");
     }
 
     ParamListener(const std::shared_ptr<rclcpp::node_interfaces::NodeParametersInterface>& parameters_interface,
-                  rclcpp::Logger logger, std::string const& prefix = "") {
+                  rclcpp::Logger logger, std::string const& prefix = "", bool initialize_params = true) {
       logger_ = logger;
       prefix_ = prefix;
+      are_parameters_initialized_ = false;
       if (!prefix_.empty() && prefix_.back() != '.') {
         prefix_ += ".";
       }
 
       parameters_interface_ = parameters_interface;
       declare_params();
+      if(initialize_params)
+        initialize_parameters();
       auto update_param_cb = [this](const std::vector<rclcpp::Parameter> &parameters){return this->update(parameters);};
       handle_ = parameters_interface_->add_on_set_parameters_callback(update_param_cb);
       clock_ = rclcpp::Clock();
     }
 
     Params get_params() const{
       std::lock_guard<std::mutex> lock(mutex_);
+      if(!are_parameters_initialized_)
+      {
+        throw std::runtime_error("Please initialize the parameters using initialize_parameters method, before getting them!");
+      }
       return params_;
     }
 
+    bool are_params_initialized() const
+    {
+      return are_parameters_initialized_;
+    }
+
     bool is_old(Params const& other) const {
       std::lock_guard<std::mutex> lock(mutex_);
       return params_.__stamp != other.__stamp;
     }
 
     StackParams get_stack_params() {
-      Params params = get_params();
+      Params params = get_internal_params_copy();
       StackParams output;
 
 {%- filter indent(width=6) %}
@@ -140,7 +152,7 @@ struct StackParams {
     }
 
     void refresh_dynamic_parameters() {
-      auto updated_params = get_params();
+      auto updated_params = get_internal_params_copy();
       // TODO remove any destroyed dynamic parameters
 {%- filter indent(width=6) %}
 {{remove_dynamic_parameters}}
@@ -153,7 +165,7 @@ struct StackParams {
     }
 
     rcl_interfaces::msg::SetParametersResult update(const std::vector<rclcpp::Parameter> &parameters) {
-      auto updated_params = get_params();
+      auto updated_params = get_internal_params_copy();
 
       for (const auto &param: parameters) {
 {%- filter indent(width=8) %}
@@ -174,11 +186,15 @@ struct StackParams {
     }
 
     void declare_params(){
-      auto updated_params = get_params();
+      auto updated_params = get_internal_params_copy();
       // declare all parameters and give default values to non-required ones
 {%- filter indent(width=6) %}
 {{declare_params}}
 {%- endfilter %}
+    }
+
+    void initialize_parameters(){
+      auto updated_params = get_internal_params_copy();
       // get parameters and fill struct fields
       rclcpp::Parameter param;
 
@@ -194,17 +210,25 @@ struct StackParams {
 
       updated_params.__stamp = clock_.now();
       update_interal_params(updated_params);
-    }
+      are_parameters_initialized_ = true;
+      }
 
     private:
       void update_interal_params(Params updated_params) {
         std::lock_guard<std::mutex> lock(mutex_);
         params_ = updated_params;
       }
 
+      Params get_internal_params_copy() const{
+        std::lock_guard<std::mutex> lock(mutex_);
+        return params_;
+      }
+
+
       std::string prefix_;
       Params params_;
       rclcpp::Clock clock_;
+      bool are_parameters_initialized_;
       std::shared_ptr<rclcpp::node_interfaces::OnSetParametersCallbackHandle> handle_;
       std::shared_ptr<rclcpp::node_interfaces::NodeParametersInterface> parameters_interface_;