Hi Ole, On Thu, 19 Sep 2002, Ole Streicher wrote: > Hello Rene! > > Rene Brun writes: > > TTree::AddFriend accepts a TTree as input. It is not clever enough > > to accept a TChain. > > Oh. I thought that a TChain is just an extended TTree (since it > inherits from a TTree). > Yes TChain inherits from TTree. A base class is not supposed to be aware of its derived classes, but it should be protected. > > However, a TChain::AddFriend accepts either a TTree or a TChain as > > argument. TTree::AddFriend should be protected against use with a TChain. > > Is there any drawback when I use a TChain instead of a TTree? Well, in your case, you already had a TChain. Simply, you cannot AddFriend a TChain to a TTree, but you can to a TChain. If you have only one file, you better use a TTree. If you have many files to be processed sequentially use a TChain. Rene Brun
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