xAODTruthParticleSlimmerGen: migration to Read/WriteHandleKeys

Generators/GeneratorFilters/GeneratorFilters/xAODTruthParticleSlimmerGen.h

 /*
-  Copyright (C) 2002-2024 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2025 CERN for the benefit of the ATLAS collaboration
 */
 
 #ifndef GENERATORFILTERS_XAODTRUTHPARTICLESLIMMERPHOGEN_H
@@ -29,11 +29,11 @@ public:
 
 private:
     /// The key for the output xAOD truth containers
-    std::string m_xaodTruthParticleContainerNameGen;
-    std::string m_xaodTruthParticleContainerName;
-    std::string m_xaodTruthEventContainerName;
+  SG::WriteHandleKey<xAOD::TruthParticleContainer> m_xaodTruthParticleContainerNameGen{this, "xAODTruthParticleContainerNameGen",  "TruthGen"};
+  SG::ReadHandleKey<xAOD::TruthParticleContainer> m_xaodTruthParticleContainerName{this, "xAODTruthParticleContainerName", "TruthParticles"};
+  SG::ReadHandleKey<xAOD::TruthEventContainer> m_xaodTruthEventContainerName{this, "xAODTruthEventContainerName", "TruthEvents"};
 
-    ToolHandle<IMCTruthClassifier> m_classif;
+  PublicToolHandle<IMCTruthClassifier> m_classif{this, "MCTruthClassifier", "MCTruthClassifier/DFCommonTruthClassifier"};
 }; // class xAODTruthParticleSlimmerGen
 
 #endif //GENERATORFILTERS_XAODTRUTHPARTICLESLIMMERPHOGEN_H

Generators/GeneratorFilters/src/xAODTruthParticleSlimmerGen.cxx

 /*
-  Copyright (C) 2002-2024 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2025 CERN for the benefit of the ATLAS collaboration
 */
 
 #include "AthenaKernel/errorcheck.h"
@@ -23,54 +23,44 @@
 
 xAODTruthParticleSlimmerGen::xAODTruthParticleSlimmerGen(const std::string &name, ISvcLocator *svcLoc)
     : AthAlgorithm(name, svcLoc)
-    , m_classif("MCTruthClassifier/DFCommonTruthClassifier")
 {
-    declareProperty("xAODTruthParticleContainerName", m_xaodTruthParticleContainerName = "TruthParticles");
-    declareProperty("xAODTruthParticleContainerNameGen", m_xaodTruthParticleContainerNameGen = "TruthGen");
-    declareProperty("xAODTruthEventContainerName", m_xaodTruthEventContainerName = "TruthEvents");
 }
 
 StatusCode xAODTruthParticleSlimmerGen::initialize()
 {
-    ATH_MSG_INFO("xAOD input TruthParticleContainer name = " << m_xaodTruthParticleContainerName);
-    ATH_MSG_INFO("xAOD output TruthParticleContainerGen name = " << m_xaodTruthParticleContainerNameGen);
-
-    ATH_CHECK(m_classif.retrieve());
+  ATH_CHECK(m_xaodTruthParticleContainerName.initialize());
+  ATH_MSG_INFO("xAOD input TruthParticleContainer name = " << m_xaodTruthParticleContainerName.key());
+  ATH_CHECK(m_xaodTruthParticleContainerNameGen.initialize());
+  ATH_MSG_INFO("xAOD output TruthParticleContainerGen name = " << m_xaodTruthParticleContainerNameGen.key());
+  ATH_CHECK(m_xaodTruthEventContainerName.initialize());
+  ATH_CHECK(m_classif.retrieve());
 
     return StatusCode::SUCCESS;
 }
 
 StatusCode xAODTruthParticleSlimmerGen::execute()
 {
-    // If the containers already exists then assume that nothing needs to be done
-    if (evtStore()->contains<xAOD::TruthParticleContainer>(m_xaodTruthParticleContainerNameGen))
-    {
-        ATH_MSG_WARNING("xAOD Gen Truth Particles are already available in the event");
-        return StatusCode::SUCCESS;
-    }
-
+  const EventContext& ctx = Gaudi::Hive::currentContext(); // As not re-entrant
     // Create new output container
-    xAOD::TruthParticleContainer *xTruthParticleContainerGen = new xAOD::TruthParticleContainer();
-    CHECK(evtStore()->record(xTruthParticleContainerGen, m_xaodTruthParticleContainerNameGen));
-    xAOD::TruthParticleAuxContainer *xTruthParticleAuxContainerGen = new xAOD::TruthParticleAuxContainer();
-    CHECK(evtStore()->record(xTruthParticleAuxContainerGen, m_xaodTruthParticleContainerNameGen + "Aux."));
-    xTruthParticleContainerGen->setStore(xTruthParticleAuxContainerGen);
-    ATH_MSG_INFO("Recorded TruthParticleContainerGen with key: " << m_xaodTruthParticleContainerNameGen);
+    SG::WriteHandle<xAOD::TruthParticleContainer> xTruthParticleContainerGen(m_xaodTruthParticleContainerNameGen, ctx);
+    ATH_CHECK(xTruthParticleContainerGen.record(std::make_unique<xAOD::TruthParticleContainer>(),
+                                                 std::make_unique<xAOD::TruthParticleAuxContainer>()));
+    ATH_MSG_INFO("Recorded TruthParticleContainerGen with key: " << m_xaodTruthParticleContainerNameGen.key());
 
     // Retrieve full TruthParticle container
-    const xAOD::TruthParticleContainer *xTruthParticleContainer;
-    if (evtStore()->retrieve(xTruthParticleContainer, m_xaodTruthParticleContainerName).isFailure())
+    SG::ReadHandle<xAOD::TruthParticleContainer> xTruthParticleContainer{m_xaodTruthParticleContainerName};
+    if ( !xTruthParticleContainer.isValid() )
     {
-        ATH_MSG_ERROR("No TruthParticle collection with name " << m_xaodTruthParticleContainerName << " found in StoreGate!");
+      ATH_MSG_ERROR("No TruthParticle collection with name " << m_xaodTruthParticleContainerName.key() << " found in StoreGate!");
         return StatusCode::FAILURE;
     }
     // Retrieve full TruthEventContainer container
-    const xAOD::TruthEventContainer *xTruthEventContainer=NULL;
-    if (evtStore()->retrieve(xTruthEventContainer, m_xaodTruthEventContainerName).isFailure())
-    {
+    SG::ReadHandle<xAOD::TruthEventContainer> xTruthEventContainer{m_xaodTruthEventContainerName};
+    if ( !xTruthEventContainer.isValid() )
+      {
         ATH_MSG_ERROR("No TruthEvent collection with name " << m_xaodTruthEventContainerName << " found in StoreGate!");
         return StatusCode::FAILURE;
-    }
+      }
 
     // Loop over full TruthParticle container
     xAOD::TruthEventContainer::const_iterator itr;