CMSSW Reference Manual

00001 
00009 #include "FWCore/Framework/interface/EDProducer.h"
00010 #include "FWCore/ParameterSet/interface/InputTag.h"
00011 #include "DataFormats/Candidate/interface/CandidateFwd.h"
00012 #include <vector>
00013 
00014 namespace edm { class ParameterSet; }
00015 namespace HepMC { class GenParticle; class GenEvent; }
00016 
00017 class GenEventScaleProducer : public edm::EDProducer {
00018  public:
00020   GenEventScaleProducer( const edm::ParameterSet & );
00021 
00022  private:
00023   void produce( edm::Event& evt, const edm::EventSetup& es );
00024   edm::InputTag src_;
00025 };
00026 
00027 #include "SimDataFormats/HepMCProduct/interface/HepMCProduct.h"
00028 #include "DataFormats/Common/interface/Handle.h"
00029 #include "FWCore/Framework/interface/Event.h"
00030 #include "FWCore/Utilities/interface/EDMException.h"
00031 #include "FWCore/ParameterSet/interface/ParameterSet.h"
00032 using namespace edm;
00033 using namespace std;
00034 using namespace HepMC;
00035 
00036 GenEventScaleProducer::GenEventScaleProducer( const ParameterSet & p ) :
00037   src_( p.getParameter<InputTag>( "src" ) ) {
00038   produces<double>();
00039 }
00040 
00041 
00042 void GenEventScaleProducer::produce( Event& evt, const EventSetup& es ) {
00043   Handle<HepMCProduct> mc;
00044   evt.getByLabel( src_, mc );
00045   const GenEvent * genEvt = mc->GetEvent();
00046   if( genEvt == 0 ) 
00047     throw edm::Exception( edm::errors::InvalidReference ) 
00048       << "HepMC has null pointer to GenEvent" << endl;
00049   auto_ptr<double> event_scale( new double(1) );
00050   (*event_scale) = genEvt->event_scale();
00051   evt.put( event_scale );
00052 }
00053 
00054 #include "FWCore/Framework/interface/MakerMacros.h"
00055 
00056 DEFINE_FWK_MODULE( GenEventScaleProducer );
00057
GenEventScaleProducer.cc
