Re: Question on TTree branches

From: Rene Brun (Rene.Brun@cern.ch)
Date: Sun Jun 29 1997 - 11:57:49 MEST


Terrence Brannon wrote:
> 
> The documentation for the TTree says
> 
> Various kinds of branches can be added to a tree:
>        A - simple structures or list of variables. (may be for C or
>         Fortran structures)
>        B - any object (inheriting from TObject). (we expect this
>         option be the most frequent)
>        C - a ClonesArray. (a specialized object for collections of
>         same class objects)
> 
> My question is: must object inherit from TObject? Or is it sufficient
> that they be ClassDef'ed and ClassImp'ed?

 case B explicitely says: object must inherit from TObject.

> 
> If they must be derived from TObject, then I assume I am forced to use
> Case A and list out every field I want as a TTree branch.
> 

 NO. When you use case B, you can specify the option split.
Each component of your object will automatically go to a separate
branch.
See example in root/test/Event 
and also:

        http://root.cern.ch/root/HowtoWriteTree.html

Rene Brun



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