I/O with TObject as virtual base

[patrickm]

Is it possible to make TObject a virtual base of MyClass and still use ROOT’s I/O facilities? This 2010 post says that the answer was “no” then:

Using TTree Branch for a class that virtually inherits

Hi all. I’d really like to use multiple virtual inheritance in my data structure classes. I have been trying to do the following: class Base { … } class Event : public virtual Base { … } fillTree{ TTree *t = new Tree(…); Event *e = new Event(); t->Branch(“eventBranch”, “Event”, &e, 32000, 99); //loop and fill some Event members t->Write(); } My code compiles, but always breaks at the TTree::Branch. If I do not virtually inherit class Base, then it completely works fine. Can anyb…

Given the discussion there, would it be correct to assume that this might be possible with ROOT6, but not with any v5-34 versions?

[pcanal]

Hi,

We have no plan to support virtual inheritance in the I/O in v5.34. After the release of ROOT 6 we are planning to review the priority for improvement in ROOT I/O (at a ROOT I/O workshop in June at CERN), the initial push will be in making the I/O usable in threaded environment and parallel merging of files. Support for virtual inheritance in the I/O is on the list of things to do but might not appear for a while (i.e. lower priority than other improvements).

Cheers,
Philippe.

[patrickm]

Thanks for the info, Philippe. FWIW, I appreciate how hard it is to balance competing requests, and that priority order certainly makes sense to me.

Patrick