#include <stdio.h>

#include <TTree.h>
#include <TChain.h>
#include <TFile.h>
#include <TSelector.h>

void write_tree(char *fn,int base){
	Int_t dat;

	fprintf(stderr,"Writing file %s, base is %d\n",fn,base);

	TFile *of=new TFile(fn,"RECREATE");
	TTree *ot=new TTree("t1","Tree 1");
	ot->Branch("DatBranch",&dat,"dat/I");
	for(int i=0;i<4;i++){
		dat=i+base;
		ot->Fill();
	}
	ot->Write();
	delete ot;
	delete of;
}

class BugSelector : public TSelector {
public:
	Int_t dat;
	TTree *fTree;
	BugSelector(){ fprintf(stderr,"new BugSelector!\n"); };
	~BugSelector(){ fprintf(stderr,"bye BugSelector!\n"); };
	virtual Bool_t Notify(){
		fprintf(stderr,"Notify()\n");
		return kTRUE;
	};
	virtual void Begin(TTree *t){ fprintf(stderr,"Begin->"); Init(t); };
	virtual void Init(TTree *t){
		fprintf(stderr,"Init(%p)\n",t);
		fTree=t;
		t->SetBranchAddress("DatBranch",&dat);
	};
	virtual void ProcessFill(Int_t entry){
		fTree->GetEntry(entry);
		fprintf(stderr,"ProcessFill(%d) -> %d\n",entry,dat);
	};
};

int main(int argc,char **argv){
	write_tree("tree1.root",100);
	write_tree("tree2.root",200);
	write_tree("tree3.root",300);

	TChain ch("t1","My Chain");
	ch.Add("tree1.root");
	ch.Add("tree2.root");
	ch.Add("tree3.root");

	BugSelector b;
	ch.Process(&b);
}