Problem with a TTree holding an user defined object

ROOT
1

Hi all,
I have a problem with a TTree having a branch which holds an object. The class (ParticleInfo) of those objects is derived from TObject and essentially contains a TClonesArray holding TParticle objects and a set of member functions which give access to the variables of the objects in the array.
I have attached the source here (ParticleInfo.cc and ParticleInfo.hh).
In my analyses I fill the tree with no problems and the output root file is just OK. The problem arise when I try to inspect the TTree with the TreeViewer or drawing histograms (with TTree::Draw()) using the class’s member functions. However if I don’t use these tools and I make analisys just retrieving the objects with SetBranchAddress and GetEntry, the member functions work perfect.
I have spent several days trying to solve this kind of problems and I would need a little help.

I have also attached a macro called analysis.C and the root file with the tree for an easy inspecting. Everything is compressed in the file test.tar.gz

Thanks in advance.
test.tar.gz (43.1 KB)

2

Hi,

This is actually an issue with the lifetime of a C++ variable. You have:

void analysis() { .... ParticleInfo *HadronInfo; tree->SetBranchAddress("HadronInfo", &HadronInfo); ... }and hence at the end of the function the TTree still hold the address to the (now defunct) variable ‘HadronInfo’. To solve the problem you simply need to call ResetBranchAddresses:

void analysis() { .... ParticleInfo *HadronInfo; tree->SetBranchAddress("HadronInfo", &HadronInfo); ... tree->ResetBranchAddresses(); }

Cheers,
Philippe.[/i]

3

Oh!
It helps… Thank you! :smiley: