[ROOT] Change in class version

From: Thomas Bretz (tbretz@astro.uni-wuerzburg.de)
Date: Mon Oct 20 2003 - 12:08:31 MEST 

Hi,

what happens, if I have two class versions

class MyClass : public TObject
{
     ClassDef(MyClass, 1)
}

and

class MyClass : public TObject
{
     TArrayI fArray;
     ClassDef(MyClass, 2)
}

Now I'm writing objects of version 1 in my file and reading the file 
using class version 2. Is the fArray data member untouched, freed, 
cleared? I'm asking, because I use such an array as a lookup table (for 
accelerating access to another array) I could make reading 'old' files 
backward compatible, by searching the other array. But therfor I must 
know whether it is an old file or not. Can I get the information by 
checking fArray.GetSize()==0?

Thanks in advance,
Thomas.

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