Add option to dump GDML

Simulation/G4Faser/G4FaserAlg/src/G4FaserAlg.cxx

@@ -200,12 +200,14 @@ void G4FaserAlg::initializeOnce()
   if(m_userLimitsSvc.retrieve().isFailure()) {
     throw std::runtime_error("Could not initialize ATLAS UserLimitsSvc!");
   }
-
-  G4LogicalVolumeStore* store = G4LogicalVolumeStore::GetInstance();
-  G4LogicalVolume* world = store->GetVolume("Faser::Faser");
-  G4GDMLParser parser {};
-  parser.Write("Faser.gdml", world);
-  ATH_MSG_ALWAYS("Wrote detector geometry to GDML file");
+  
+  if (!m_gdmlFilename.empty())
+  {
+    G4LogicalVolumeStore* store = G4LogicalVolumeStore::GetInstance();
+    G4LogicalVolume* world = store->GetVolume("Faser::Faser");
+    G4GDMLParser parser {};
+    parser.Write(m_gdmlFilename.value(), world);
+  }
 
   if (m_activateParallelGeometries) {
     G4VModularPhysicsList* thePhysicsList=dynamic_cast<G4VModularPhysicsList*>(m_physListSvc->GetPhysicsList());

Simulation/G4Faser/G4FaserAlg/src/G4FaserAlg.h

@@ -120,6 +120,8 @@ private:
   /// Activate multi-threading configuration
   Gaudi::Property<bool> m_useMT{this,"MultiThreading",  false, "Multi-threading specific settings"};
   Gaudi::Property<bool> m_activateParallelGeometries{this, "ActivateParallelWorlds", false, "Toggle on/off the G4 parallel geometry system"};
+  /// Dump GDML file
+  Gaudi::Property<std::string> m_gdmlFilename{this, "GDMLfile", "", "GDML geometry file to write"};
   /// Random number service
   ServiceHandle<IAthRNGSvc> m_rndmGenSvc{this, "AtRndmGenSvc", "AthRNGSvc", ""}; // TODO rename property
   /// Random Stream Name