/// \file
/// \ingroup tutorial_tree
/// \notebook -nodraw
/// Simple Event class example
///
/// execute as: .x tree0.C++
///
///  You have to copy it first to a directory where you have write access!
///  Note that .x tree0.C cannot work with this example
///
/// ### Effect of ClassDef() and ClassImp() macros
///
/// After running this macro create an instance of Det and Event
///
/// ~~~
///   Det d;
///   Event e;
/// ~~~
///
/// now you can see the effect of the  ClassDef() and ClassImp() macros.
/// (for the Det class these commands are commented!)
/// For instance 'e' now knows who it is:
///
/// ~~~
///   cout<<e.Class_Name()<<endl;
/// ~~~
///
/// whereas d does not.
///
/// The methods that are added by the ClassDef()/Imp() marcro can be listed with
///
/// ~~~
/// .class
///   .class Event
///   .class Det
/// ~~~
///
/// \macro_code
///
/// \author Heiko.Scheit@mpi-hd.mpg.de

#include <TRandom.h>
#include <TTree.h>
#include <TCanvas.h>
#include <TStyle.h>

#include <Riostream.h>

//ClassImp(Det)

//class Event { //TObject is not required by this example
class Event : public TObject {
public:

  Double_t e; //energy; // say there are two detectors (a and b) in the experiment
  Double_t t; //time;
  ClassDef(Event,1)
};

ClassImp(Event)

void tree0() {
  // create a TTree
  TFile *outfile = new TFile("testtree.root","RECREATE");
  TTree *tree = new TTree("tree","treelibrated tree");

  // create a branch with energy
  TClonesArray *events = new TClonesArray("Event");
  tree->Branch("t.",&events);

  // fill some events with random numbers
  Int_t nevent=10000;
  for (Int_t iev=0;iev<nevent;iev++) {
    events->Clear("C");

    if (iev%1000==0) cout<<"Processing event "<<iev<<"..."<<endl;
    new((*events)[0]) Event();
    Float_t ea,eb;
    gRandom->Rannor(ea,eb); // the two energies follow a gaus distribution
    ((Event*) events->At(0))->e=ea;
    ((Event*) events->At(0))->t=gRandom->Rndm();  // random

    tree->Fill();  // fill the tree with the current event
  }

  tree->Write();
  outfile->Close();
}