TTree::Draw and functions

ROOT
6

Hi, I have a somewhat similar question. I’m working with a tree whose branches are collection.

I’m trying to do something like:
tree->Draw(“Cone4H1TowerJets.pt()”, “f(Cone4H1TowerJets)>0”);

I get different root reactions, depending on the way f is defined:

  1. double f(const JetCollection *jets)
    Error in TTreeFormula::Compile: Bad numerical expression :
    “f(Cone4H1TowerJets)”

if I use @Cone4H1TowerJets in the selection argument of Draw:
Error in TTreeFormula::Compile: Bad numerical expression :
“f(@Cone4H1TowerJets)”

same thing without the const.

  1. double f(JetCollection jets)
    no errors, but inside f, jets.size() is always 0
    same thing with const.
    same thing with @

  2. double f( JetCollection &jets)
    segmentation fault
    same thing with const
    same thing with @

I was also trying to use MakeProxy, but I get punched in the face:

root [1] tree->MakeProxy(“proxytest01”, “somefunc.C”, “”, “nohist”);
Fatal in ROOT::TBranchProxyClassDescriptor:: strcmp(fInfo->GetName(), type)==0 violated at line 117 of `treeplayer/src/TBranchProxyClassDescriptor.cxx’
aborting
… … …

root version is 5.18/00a btw.
Thanks,
Raz