rtt_rosparam: implement updated() and other PR comments

The patch moves the part of the set( new_value) implementation
to updated() such that when using ref_t set() the user can call
updated() and make the ROS parameter actually be updated with
the new value.

Author: spd-intermodalics

rtt_rosparam/CMakeLists.txt

@@ -10,20 +10,14 @@ pkg_search_module(EIGEN3 REQUIRED eigen3)
 include_directories(
   include
   ${catkin_INCLUDE_DIRS}
-  ${EIGEN3_INCLUDE_DIRS})
-
-# Add the data source header
-orocos_library(ros_param_data_source src/ros_param_data_source.cpp)
-target_link_libraries(ros_param_data_source
-  ${catkin_LIBRARIES}
+  ${EIGEN3_INCLUDE_DIRS}
 )
 
-  # build ROS param as a separate service
+# build ROS param as a separate service
 orocos_service(rtt_rosparam src/rtt_rosparam_service.cpp)
 target_link_libraries(rtt_rosparam 
 #  ${OROCOS-RTT_RTT-MARSHALLING_LIBRARY} 
   ${catkin_LIBRARIES}
-  ros_param_data_source
 )
 
 # Generate install targets and pkg-config files

rtt_rosparam/README.md

@@ -42,7 +42,7 @@ policy (see below).
 ##### Operations for setting all properties
 * `setAll()` or `setAllComponentPrivate()` Stores all properties of this component (and its sub-services)
   on the ROS parameter server from the similarly-named property in the **COMPONENT**'s private namespace.
-* `setAllRelative()`` Stores all properties of this component (and its sub-services)
+* `setAllRelative()` Stores all properties of this component (and its sub-services)
   on the ROS parameter server from the similarly-named property in the relative namespace.
 * `setAllAbsolute()` Stores all properties of this component (and its sub-services)
   on the ROS parameter server from the similarly-named property in the absolute namespace.
@@ -72,13 +72,13 @@ policy (see below).
 
 ##### Operations to create properties linked to a ROS param
 
-The following operations of the `rosparam` service can be used to create Properties
+The following operations of the `rosparam` service can be used to create properties
 in the owner component that link to ROS parameters. When the properties are
 `evaluate()`-d through `get()` or `set()`, the ROS parameter server is queried.
 
 **IMPORTANT** Setting or getting the value of a ROS parameter through a
-Property is a non real-time safe operation and therefore it shouldn't be used
-in the `updateHook()` of a real-time periodic component.
+property is a non real-time safe operation and therefore it shouldn't be used
+from within a real-time component.
 
 * `addRosParamProperty_type_(name)` Adds a property of type `_type_` with name `name` to the owning task context which is linked to the ROS parameter with the same name in a `Relative` namespace resolution context.
 * `addRosParamProperty_type_Relative(name)` Adds a property of type `_type_` with name `name` to the owning task context which is linked to the ROS parameter with the same name in a `Relative` namespace resolution context.

rtt_rosparam/include/rtt_rosparam/ros_param_data_source.hpp

@@ -34,6 +34,7 @@
 #include "rtt/internal/DataSource.hpp"
 #include "rtt/internal/DataSourceTypeInfo.hpp"
 #include "rtt/internal/Reference.hpp"
+#include "rtt/Logger.hpp"
 
 #include "ros/ros.h"
 #include "ros/param.h"
@@ -68,9 +69,7 @@ class RosParamDataSource
   mutable typename internal::DataSource<T>::value_t mcached_data_;
 
 public:
-  /**
-   * Use shared_ptr.
-   */
+
   typedef boost::intrusive_ptr< RosParamDataSource<T> > shared_ptr;
 
   ~RosParamDataSource()
@@ -90,12 +89,10 @@ class RosParamDataSource
 
   bool evaluate() const
   {
-    T return_value;
-    if (!ros::param::getCached(mparam_name_, return_value)) {
-      throw std::out_of_range("The parameter " + mparam_name_ + " cannot be fetched.");
+    if (!ros::param::getCached(mparam_name_, mcached_data_)) {
+      RTT::log(RTT::Error) << "The value of parameter " + mparam_name_ + " could not be fetched." << RTT::endlog();
       return false;
     }
-    mcached_data_ = return_value;
     return true;
   }
 
@@ -115,15 +112,22 @@ class RosParamDataSource
   void set( typename internal::AssignableDataSource<T>::param_t t )
   {
     set() = t;
-    ros::param::set(mparam_name_, t);
+    updated();
   }
 
-  // There is not referred element, no allocation exists for this data source and it is not an alias.
+  // There is not referred element, no allocation exists for this data source
+  // and it is not an alias.
+  // After working with the reference, if something was assigned, the data
+  // source may need a call to updated() after set()
   typename internal::AssignableDataSource<T>::reference_t set()
   {
     return mcached_data_;
   }
 
+  void updated() {
+    ros::param::set(mparam_name_, mcached_data_);
+  }
+
   virtual RosParamDataSource<T>* clone() const
   {
     return new RosParamDataSource<T>(this->mparam_name_);

rtt_rosparam/src/ros_param_data_source.cpp

@@ -251,18 +251,18 @@ class ROSParamService: public RTT::Service
   /**
    * Adds a ROS parameter of supported types by ROS param as a property to this
    * bag.
-   * A Property is created which causes contents of the
-   * property always to be in sync
-   * with the contents of the ROS parameter.
-   * @param name The name of this property
+   * The new property mirror the value of the respective ROS parameter of the
+   * name.
+   * Setting the value of the property sets the ROS parameter, and evaluating it
+   * loads the current value from the ROS parameter server.
+   * @param name The name of the ROS parameter and the property to be added.
    * @return the Property object by reference, which you can further query or document.
    */
   template<typename T, ResolutionPolicy P>
   Property<T>& addRosParamProperty( const std::string& name) {
     const std::string resolved_name = resolvedName(name,P);
     typename internal::AssignableDataSource<T>::shared_ptr datasource( new rtt_rosparam::RosParamDataSource<T>(resolved_name) );
-    Property<T>* p = new Property<T>(name,"", datasource);
-    p->doc("Property generated by rosparam attached to parameter: " + resolved_name);
+    Property<T>* p = new Property<T>(name, "Property generated by rosparam attached to parameter: " + resolved_name, datasource);
     this->getOwner()->properties()->ownProperty( p );
     return *p;
   }