Writing TObject-derived objects to file does not store the object's title #9989
Description
Describe the bug
Following #8934, when writing TObject-derived objects to a TFile, their title is correctly stored as the corresponding TKey's title, so that when listing the contents of the file it is properly displayed:
(base) vpadulan@fedora: root
------------------------------------------------------------------
| Welcome to ROOT 6.27/01 https://root.cern |
| (c) 1995-2021, The ROOT Team; conception: R. Brun, F. Rademakers |
| Built for linuxx8664gcc on Feb 16 2022, 23:26:00 |
| From heads/master@v6-25-02-553-g21fb792ac7 |
| With c++ (GCC) 11.2.1 20220127 (Red Hat 11.2.1-9) |
| Try '.help', '.demo', '.license', '.credits', '.quit'/'.q' |
------------------------------------------------------------------
root [0] TFile f{"myfile.root", "recreate"};
root [1] TH1F h{"myname","mytitle", 42, 13, 77};
root [2] f.WriteObject(&h, "myhisto");
root [3] f.Close()
root [4] .q
(base) vpadulan@fedora: rootls -lt myfile.root
TH1F Feb 24 15:59 2022 myhisto;1 "mytitle"In PyROOT this still does not happen
(base) vpadulan@fedora: python
Python 3.9.7 | packaged by conda-forge | (default, Sep 29 2021, 19:20:46)
[GCC 9.4.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import ROOT
>>> a = ROOT.TFile("myfile.root", "recreate")
>>> h = ROOT.TH1F("myname","mytitle", 42, 13, 77)
>>> a.WriteObject(h, "myhisto")
279
>>> a.Close()
>>> quit()
(base) vpadulan@fedora: rootls -lt myfile.root
TH1F Feb 24 15:58 2022 myhisto;1 "object title" The offending code is in the pythonization of TDirectory::WriteObject defined within cppyy:
root/bindings/pyroot/pythonizations/src/TDirectoryPyz.cxx
Lines 51 to 55 in cea0019
which only uses WriteObjectAny since the actual type of the object is lost at that point (it's a void*).
Expected behavior
The pythonized version of WriteObject should work as its C++ counterpart
To Reproduce
Code above should be fine whenever ROOT is built with a version that includes commits of #8934
Notes
The linked PR proposes a fix