D_xy: make it possible to add a desription

include/PropertyDescription.h

@@ -122,6 +122,7 @@ namespace ChimeraTK {
   struct XyDescription : public PropertyDescription, public PropertyAttributes {
     ChimeraTK::RegisterPath xSource;
     ChimeraTK::RegisterPath ySource;
+    std::string description;
 
     XyDescription(ChimeraTK::RegisterPath const& xSource_ = "", ChimeraTK::RegisterPath const& ySource_ = "",
         std::string const& location_ = "", std::string const& name_ = "", bool hasHistory_ = true)

src/DoocsPVFactory.cc

@@ -220,6 +220,9 @@ namespace ChimeraTK {
         getDecorator<float>(xProcessVariable, DecoratorType::C_style_conversion),
         getDecorator<float>(yProcessVariable, DecoratorType::C_style_conversion), _updater));
 
+    if(not xyDescription.description.empty())
+      boost::dynamic_pointer_cast<DoocsXy>(doocsPV)->description(xyDescription.description);
+
     doocsPV->set_ro_access();
 
     return doocsPV;

src/VariableMapper.cc

@@ -265,6 +265,9 @@ namespace ChimeraTK {
     auto xyDescription = std::make_shared<XyDescription>(xAbsoluteSource, yAbsoluteSource, locationName, name, false);
     processHistoryAndWritableAttributes(xyDescription, xyXml, locationName);
 
+    auto descriptionNode = xyXml->get_first_child("description");
+    xyDescription->description = getContentString(descriptionNode);
+
     addDescription(xyDescription, {xAbsoluteSource, yAbsoluteSource});
   }