Re: [ROOT] persistency of TChain

From: Rene Brun (Rene.Brun@cern.ch)
Date: Fri Jun 16 2000 - 11:25:42 MEST


Hi Peter,
I have implemented TChain::Streamer such that a TChain can be saved
to a Root file.

Rene Brun

Peter Steinberg wrote:
> 
> hello again -
> 
> When I make a TChain out of several files, I would like to
> store the chain configuration in a root file rather than
> in a macro.  Thus, I tried to write out the chain itself to
> a root file.  However, when i read it back from file i can't
> seem to get the tree back:
> 
> i get all of my files:
> 
> root [4] TrgTree->ls()
> OBJ: TChainElement      TrgTree $TRGTREE/TrgTree_003432s000.root : 0
> OBJ: TChainElement      TrgTree $TRGTREE/TrgTree_003432s001.root : 0
> OBJ: TChainElement      TrgTree $TRGTREE/TrgTree_003433s000.root : 0
> ...
> 
> (NB, the environmental variable TRGTREE is defined already).  However
> I can't get the tree out:
> 
> root [5] TrgTree->GetTree()
> (class TTree*)0x0
> root [6] TrgTree.Draw("Run")
> 
>  *** Break *** segmentation violation
> Root >
> 
> Is there a trick to telling the chain to re-initialize itself
> with the tree?
> 
> - Peter
> 
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> Dr. Peter A. Steinberg                        Brookhaven National Laboratory
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