[HF] Prepare HistFactory for ROOT without implicit ownership #20922
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guitargeek
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Jan 16, 2026
| TFile* file = new TFile("dataDriven.root", "RECREATE"); | ||
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| TH1F* FlatHist = new TH1F("FlatHist","FlatHist", 2,0,2); | ||
| FlatHist->SetDirectory(file); |
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I don't get it yet 🙂 If you later explicitly write the histograms with file->WriteTObject(histo), why do you need to do SetDirectory(file) before?
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You indeed don't need it to write, but you do need it to destroy the histogram. Alternatively, you can of course take the ownership "manually".
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Let me do a solution that doesn't need SetDirectory
If implicit object ownership gets in TDirectories gets switched off, the example histograms need to be added to directories or written explicitly.
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git clang-format applied enough changes to make it worth formatting the entire file.
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makeExample.CtutorialBy making the writes explicit, the tests become independent of gDirectory and whether or not histograms register themselves.