TNtupleD maximum number of branches


I noticed that the number of branches that can be automatically created when constructing a TNtupleD using the TNtupleD(const char*, const char*, const char*, Int_t) constructor is limited to 1000. This is hard coded in the constructor. And it is not really simple to add extra branches to a TNtupleD.

Is this limitation a motivated decision or simply a “random” choice ? And in the latter case, is it possible to update TNtupleD to solve this issue ? (I can propose a workaround with no limit on the number of branches).


When you have a large number of branches, use TTree directly. It will be simpler.
I have clarified this point in the documentation of the class.