SetBranchAddress multiple addresses?

I would like to link multiple variables to a single tree branch.
It seems to work in interactive, but I have to use TTree::SetMakeClass(1);

        TTree *t1 = _file0->Get("mytree");
        double Zvtx, Zvtx2;
        t1->SetBranchAddress("vertex.z", &Zvtx);
        t1->SetBranchAddress("vertex.z", &Zvtx2);
        cout << Zvtx << " " << Zvtx2 << endl;

0.00 -0.244

In practive the second setbranchaddress is called within a class. So I cannot just play with pointers in order to copy Zvtx pointer into Zvtx2. Of course this would be easy to do.
Knowing that the 2 zvtx variables might not exists at the same moment. Is there a way to copy it safely?

Edit: I saw it is possible to set an alias, but it seems I cannot use it with SetBranchAddress
Edit-2: I tried to use TBranchElement::GetAddress(), it returns a char* but I don’t know how to use it to get the corresponding object

I would say it’s not possible, but maybe @Axel or @pcanal could know a way…


I just figured out. It is not very clean but I do the following:

if( t->GetBranch("branchname")->GetAddress()  != NULL )
cout << *((double*) t->GetBranch("branchname")->GetAddress() << endl;

Oh, OK, sorry, I replied to the multiple addresses question…

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Correct. Alias are for TTree::Draw.

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