GaudiPluginService: add DECLARE_COMPONENT_PROPERTY macro

`DECLARE_COMPONENT_PROPERTY( MyComponent, "myprop", "value" )` can be
used to set properties on already declared components.

GaudiPluginService/include/Gaudi/PluginServiceV2.h

@@ -154,11 +154,21 @@ namespace Gaudi {
         ::Gaudi::PluginService::v2::Details::stringify_id( id ) };                                                     \
   }
 
+#define _PS_V2_DECLARE_COMPONENT_PROPERTY( id, name, value )                                                           \
+  namespace {                                                                                                          \
+    struct _PS_V2_INTERNAL_SET_PROPERTY {                                                                              \
+      _PS_V2_INTERNAL_SET_PROPERTY() {                                                                                 \
+        ::Gaudi::PluginService::v2::Details::Registry::instance().addProperty( #id, name, value );                     \
+      }                                                                                                                \
+    } _ps_v2_internal_set_property;                                                                                    \
+  }
+
 #if GAUDI_PLUGIN_SERVICE_USE_V2
 #  define DECLARE_COMPONENT( type ) _PS_V2_DECLARE_COMPONENT( type )
 #  define DECLARE_COMPONENT_WITH_ID( type, id ) _PS_V2_DECLARE_COMPONENT_WITH_ID( type, id )
 #  define DECLARE_FACTORY( type, factory ) _PS_V2_DECLARE_FACTORY( type, factory )
 #  define DECLARE_FACTORY_WITH_ID( type, id, factory ) _PS_V2_DECLARE_FACTORY_WITH_ID( type, id, factory )
+#  define DECLARE_COMPONENT_PROPERTY( id, name, value ) _PS_V2_DECLARE_COMPONENT_PROPERTY( id, name, value )
 #endif
 
 #endif //_GAUDI_PLUGIN_SERVICE_H_

GaudiPluginService/tests/src/UseCasesLib.cpp

 /***********************************************************************************\
-* (c) Copyright 2013-2019 CERN for the benefit of the LHCb and ATLAS collaborations *
+* (c) Copyright 2013-2022 CERN for the benefit of the LHCb and ATLAS collaborations *
 *                                                                                   *
 * This software is distributed under the terms of the Apache version 2 licence,     *
 * copied verbatim in the file "LICENSE".                                            *
@@ -55,6 +55,11 @@ public:
 
 DECLARE_COMPONENT( Component2 )
 
+// deprecated
+class ObsoleteComponent : public Base {};
+DECLARE_COMPONENT( ObsoleteComponent )
+DECLARE_COMPONENT_PROPERTY( ObsoleteComponent, "deprecated", "this component is obsolete" )
+
 // namespaces
 namespace Test {
   class ComponentA : public Base {};

GaudiPluginService/tests/src/UseCasesTests.cpp

@@ -65,6 +65,7 @@ BOOST_AUTO_TEST_CASE( deprecated ) {
 
   reg.setError( "deprecated" );
   BOOST_CHECK( Base::Factory::create( "Component0" ) == nullptr );
+  BOOST_CHECK( Base::Factory::create( "ObsoleteComponent" ) == nullptr );
 
   reg.unsetError( "deprecated" );
   reg.addProperty( "Component0", "deprecated", "this factory will be removed in Gaudi v99" );