Renaming leaf in branch

[ivankp]

I have a TTree with a TBranch that was written like this:

t3->Branch("me_wgt",&m_mewgt,"me_wtg/D");

Is there a way to rename that leaf, so that it has the same name as the branch, without copying the file?

I tried

TFile *_file0 = TFile::Open("file.root","update");
t3->GetLeaf("me_wtg")->SetName("me_wgt");
_file0->Write();

but that had no effect.

t3->GetBranch("me_wgt")->GetLeaf("me_wtg");

returns nullptr;

[pcanal]

It is possible but delicate. What is the purpose of the rename?
It might be simpler to alias it:

tree->SetAlias("me_wgt","me_wtg");

Cheers,
Philippe.

[ivankp]

I want to use a TTreeReader, but with the leaf’s name not matching that of the branch it throws an error.

If it’s possible, can you tell me how to do it?

[pcanal]

Fortunately, it turns out I was mis-remembering or so it seems.

Your example as-is works for me. Note that most tools use the branch name rather than the leaf name so you need to change both.

_file0->Write();

Most likely it is failing simply that the file is not open for update.

Cheers,
Philippe.