[ROOT] Warning message from ROOT 4.00/04

From: Hyeongryul So (alphard@ieplab.snu.ac.kr)
Date: Mon May 03 2004 - 03:39:46 MEST 

Hi,

I have been using ROOT on my Linux box (Fedora Core 1). After upgrading my
installation of ROOT from 4.00/03 to 4.00/04, I received this warning
messages while reading files generated by the previous versions of ROOT.

        root [0] TFile* file = new TFile("check.root", "read")
        Warning in <TStreamerInfo::BuildCheck>: 
                The StreamerInfo of class TAttLine read from file check.root
                has the same version (=1) as the active class but a different checksum.
                You should update the version to ClassDef(TAttLine,2).
                Do not try to write objects with the current class definition,
                the files will not be readable.
        
        Warning in <TStreamerInfo::BuildCheck>: 
                The StreamerInfo of class TAttMarker read from file check.root
                has the same version (=1) as the active class but a different checksum.
                You should update the version to ClassDef(TAttMarker,2).
                Do not try to write objects with the current class definition,
                the files will not be readable.

Attached is the sample data file which contains only one histogram and was
generated by ROOT 4.00/03. It seems that the change in class TCint is
responsible for the message.

        2004-04-27 15:15  rdm
        	* meta/: inc/TCint.h, src/TCint.cxx:
        	use new Cint autoloading interface (G__set_class_autoloading_table()) and
        	callback mechanism to load the needed library (TCint::AutoLoadCallback()).

It worries me that the new mechanism might not be backward-compatible; is it
safe to use ROOT 4.00/04 with data files generated by older version of ROOT?

Thanks,
H. So.

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