Details
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Bug
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Status: Closed (View Workflow)
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High
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Resolution: Fixed
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master
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None
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None
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None
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any
Description
If a TTree contains
- a branch "v" with a leaf "a", created with t.Branch("v", &a, "a/I")
- a branch "w" containing a split struct that has a datamember "v" with a datamember "a"
constructing TTreeReaderValue<int>(r, "v.a") attaches the reader to "w.v.a" instead of "v.a". Note that in this scenario there is no way to access "v.a", because constructing TTreeReaderValue<int>(r, "v") attaches to "w.v" (and anyway, if it attached to the top level branch "v", it would yield the following error message:
Error in <TTreeReaderValueBase::GetBranchDataType()>: The branch v was created using a leaf list and cannot be represented as a C++ type. Please access one of its siblings using a TTreeReaderArray:
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Error in <TTreeReaderValueBase::GetBranchDataType()>: v.a
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The reproducer requires two files:
// test_read_leaves.h
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struct V { |
int a = 42; |
};
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struct W { |
int b; |
V v;
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};
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#include <TTree.h>
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#include <TFile.h>
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#include <TTreeReader.h>
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#include <TTreeReaderValue.h>
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#include <TROOT.h>
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#include <iostream>
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#include "test_read_leaves.h"
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using namespace ROOT::Experimental; |
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int main() |
{
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// create input file |
{
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TFile f("test_read_leaves.root", "RECREATE"); |
TTree t("t", "t"); |
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V v;
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v.a = 1;
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t.Branch("v", &v, "a/I"); |
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// comment these three lines to read the correct value |
gROOT->ProcessLine(".L test_read_leaves.h+"); |
W w;
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t.Branch("w", &w); |
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t.Fill();
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t.Write();
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}
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// read "v.a" |
TFile f("test_read_leaves.root"); |
TTreeReader r("t", &f); |
TTreeReaderValue<int> rv(r, "v.a"); |
r.Next();
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if (*rv == 1) |
std::cout << "v.a was read" << std::endl; |
else if (*rv == 42) |
std::cout << "w.v.a was read" << std::endl; |
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return 0; |
}
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