Hi Chris,
I do not see a problem with this basic example. Using your generator
example, I created the two files testSel.h and testSel.C (in attachment).
I modified testSel.C in ProcessCut, adding the two statements:
b_p->GetEntry(entry);
printf("p=%f\n",p);
then, from an interactive ROOT session, I did
root [0] TFile *f= new TFile("test.root");
root [1] TTree *t= (TTree*)f->Get("test");
root [2] .L testSel.C++
root [3] testSel selector;
root [4] t->Process(&selector);
This gives:
p=3.200000
p=2.100000
p=2.400000
Rene Brun
Chris Roat wrote:
>
> Hi ROOTers,
>
> I am having a problem using the code generated by TTree::MakeSelector in a
> standalone application. Below I show how I create a very basic tree with
> one branch, "p", that is filled with three entries. I then run
> MakeSelector to generate an analysis skeleton. I add ClassDef(test,1) and
> ClassImp(testSel) macros to the resulting skeleton files.
>
> Making an appropriate LinkDef file, I compile and run the simple main
> program, also shown below. It runs fine, but at this point the skeleton
> is still empty - a sterile application. I add the following simple line
> to testSel::ProcessCut(),
>
> b_p->GetEntry(entry);
>
> which is, I think, supposed to fill the branch with the entry - based on
> my experience on the command line. The code compiles without hassle, but
> then I get a seg fault when the new line runs. The traceback is shown
> below.
>
> I am running on a linux box with g++-2.95.2, ROOT version 3.01/06.
>
> Can someone point me to what I am doing wrong? Thanks much,
> Chris
>
> // create a basic tree
>
> hfile = new TFile("test.root","RECREATE");
> tree = new TTree("test","A Tree");
> Float_t p;
> b = tree->Branch("p", &p, "p/F" );
> p= 3.2; tree->Fill();
> p= 2.1; tree->Fill();
> p= 2.4; tree->Fill();
> hfile->Write();
> tree->MakeSelector("testSel")
>
> // main program
>
> #include <TTree.h>
> #include <TFile.h>
> #include "testSel.h"
>
> int main() {
>
> TROOT myroot("myroot","Required TROOT object");
> TFile *f= new TFile("test.root");
> TTree *t= (TTree*)f->Get("test");
> testSel selector;
> t->Process(&selector);
> return 0;
>
> }
>
> // traceback
>
> (gdb) where
> #0 0x400d8204 in TBuffer::ReadFastArray () from
> /afs/slac.stanford.edu/g/babar/package/root/3.01-06/Linux2/lib/libCore.so
> #1 0x40a6d3b6 in TLeafF::ReadBasketExport () from
> /afs/slac.stanford.edu/g/babar/package/root/3.01-06/Linux2/lib/libTree.so
> #2 0x40a5c397 in TBranch::GetEntryExport () from
> /afs/slac.stanford.edu/g/babar/package/root/3.01-06/Linux2/lib/libTree.so
> #3 0x804b5e3 in testSel::ProcessCut (this=0xbfffeec0, entry=0) at
> testSel.C:49
> #4 0x40dafd4d in TTreePlayer::Process () from
> /afs/slac.stanford.edu/g/babar/package/root/3.01-06/Linux2/lib/libTreePlayer.so
> #5 0x40a766ab in TTree::Process () from
> /afs/slac.stanford.edu/g/babar/package/root/3.01-06/Linux2/lib/libTree.so
> #6 0x804b33f in main () at pid.C:11
//////////////////////////////////////////////////////////
// This class has been automatically generated
// (Thu Oct 18 09:00:54 2001 by ROOT version3.02/01)
// from TTree test/A Tree
// found on file: test.root
//////////////////////////////////////////////////////////
#ifndef testSel_h
#define testSel_h
#include <TROOT.h>
#include <TChain.h>
#include <TFile.h>
#include <TSelector.h>
class testSel : public TSelector {
public :
TTree *fChain; //!pointer to the analyzed TTree or TChain
//Declaration of leaves types
Float_t p;
//List of branches
TBranch *b_p; //!
testSel(TTree *tree=0) {;}
~testSel() {;}
void Begin(TTree *tree);
void Init(TTree *tree);
Bool_t Notify();
Bool_t ProcessCut(Int_t entry);
void ProcessFill(Int_t entry);
void Terminate();
};
#endif
#ifdef testSel_cxx
void testSel::Init(TTree *tree)
{
// Set branch addresses
if (tree == 0) return;
fChain = tree;
fChain->SetMakeClass(1);
fChain->SetBranchAddress("p",&p);
}
Bool_t testSel::Notify()
{
// called when loading a new file
// get branch pointers
b_p = fChain->GetBranch("p");
return kTRUE;
}
#endif // #ifdef testSel_cxx
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