Read only parameters

rclcpp/CMakeLists.txt

@@ -210,10 +210,6 @@ if(BUILD_TESTING)
     )
     target_link_libraries(test_node_global_args ${PROJECT_NAME})
   endif()
-  ament_add_gtest(test_node_initial_parameters test/test_node_initial_parameters.cpp)
-  if(TARGET test_node_initial_parameters)
-    target_link_libraries(test_node_initial_parameters ${PROJECT_NAME})
-  endif()
   ament_add_gtest(test_parameter_events_filter test/test_parameter_events_filter.cpp)
   if(TARGET test_parameter_events_filter)
     ament_target_dependencies(test_parameter_events_filter

rclcpp/include/rclcpp/exceptions.hpp

@@ -185,14 +185,35 @@ class EventNotRegisteredError : public std::runtime_error
 class InvalidParametersException : public std::runtime_error
 {
 public:
-  // Inherit constructors from runtime_error;
+  // Inherit constructors from runtime_error.
   using std::runtime_error::runtime_error;
 };
 
-/// Throwing if passed parameter value is invalid.
+/// Thrown if passed parameter value is invalid.
 class InvalidParameterValueException : public std::runtime_error
 {
-  // Inherit constructors from runtime_error;
+  // Inherit constructors from runtime_error.
+  using std::runtime_error::runtime_error;
+};
+
+/// Thrown if parameter is already declared.
+class ParameterAlreadyDeclaredException : public std::runtime_error
+{
+  // Inherit constructors from runtime_error.
+  using std::runtime_error::runtime_error;
+};
+
+/// Thrown if parameter is not declared, e.g. either set or get was called without first declaring.
+class ParameterNotDeclaredException : public std::runtime_error
+{
+  // Inherit constructors from runtime_error.
+  using std::runtime_error::runtime_error;
+};
+
+/// Thrown if parameter is immutable and therefore cannot be undeclared.
+class ParameterImmutableException : public std::runtime_error
+{
+  // Inherit constructors from runtime_error.
   using std::runtime_error::runtime_error;
 };