Geant4 User's Guide for Application Developers - Geant4 - CERN

User Actions6.3.1. G4VUserEventInformationG4VUserEventInformation is an abstract class from which the user can derive his/her own concrete class for storinguser information associated with a G4Event class object. It is the user's responsibility to construct a concrete classobject and set the pointer to a proper G4Event object.Within a concrete implementation of G4UserEventAction, the SetUserEventInformation() method ofG4EventManager may be used to set a pointer of a concrete class object to G4Event, given that the G4Event objectis available only by "pointer to const". Alternatively, the user may modify the GenerateEvent() method of his/herown RunManager to instantiate a G4VUserEventInformation object and set it to G4Event.The concrete class object is deleted by the Geant4 kernel when the associated G4Event object is deleted.6.3.2. G4VUserTrackInformationThis is an abstract class from which the user can derive his/her own concrete class for storing user informationassociated with a G4Track class object. It is the user's responsibility to construct a concrete class object and setthe pointer to the proper G4Track object.Within a concrete implementation of G4UserTrackingAction, the SetUserTrackInformation() method ofG4TrackingManager may be used to set a pointer of a concrete class object to G4Track, given that the G4Trackobject is available only by "pointer to const".The ideal place to copy a G4VUserTrackInformation object from a mother track to its daughter tracks isG4UserTrackingAction::PostUserTrackingAction().Example 6.9. Copying G4VUserTrackInformation from mother to daughter tracksvoid RE01TrackingAction::PostUserTrackingAction(const G4Track* aTrack){G4TrackVector* secondaries = fpTrackingManager->GimmeSecondaries();if(secondaries){RE01TrackInformation* info = (RE01TrackInformation*)(aTrack->GetUserInformation());size_t nSeco = secondaries->size();if(nSeco>0){for(size_t i=0; i < nSeco; i++){RE01TrackInformation* infoNew = new RE01TrackInformation(info);(*secondaries)[i]->SetUserInformation(infoNew);}}}}The concrete class object is deleted by the Geant4 kernel when the associated G4Track object is deleted. In casethe user wants to keep the information, it should be copied to a trajectory corresponding to the track.6.3.3. G4VUserPrimaryVertexInformation andG4VUserPrimaryTrackInformationThese abstract classes allow the user to attach information regarding the generated primary vertex and primaryparticle. Concrete class objects derived from these classes should be attached to G4PrimaryVertex andG4PrimaryParticle class objects, respectively.The concrete class objects are deleted by the Geant4 Kernel when the associated G4PrimaryVertex orG4PrimaryParticle class objects are deleted along with the deletion of G4Event.203