#include "TObject.h"
#include "TTree.h"
#include "TRandom.h"

class MyEvent : public TObject {
  public:
    MyEvent() : m_value(0.) {}
    double value() const { return m_value; }
    void setValue(double val) { m_value = val; }

  private:
    double m_value;
    ClassDef(MyEvent,1);
};

TTree* create_tree() {
  MyEvent* ev = new MyEvent;
  TTree* tree = new TTree("tree", "tree");
  tree->Branch("ev", "MyEvent", &ev);
  for (int i=0; i<100; ++i) {
    ev->setValue(gRandom->Uniform());
    tree->Fill();
  }
  tree->ResetBranchAddresses();
  return tree;
}

double testor(const MyEvent* event) {
  return event->value() + 1.;
}