Re: File I/O

From: Thomas Bretz <>
Date: Thu, 07 Jul 2005 17:57:11 +0200

Hi Philippe,

> I am a little confused. The symptom you describe is what I expect
> when reading 4.0 files with ROOT 3. However we were wondering about:

That's what it is for. It is working vice versa.

>>but a lot of people having Software which doesn't work with the 
>>newer version anymore (for several reasons).

> What are those reason why their Software does not work with ROOT 4?

It simply doesn't compile anymore, because the meaning of functions has changes (eg TMatrix::IsValid), const-qualifiers have changed, etc.

Maybe I should have said "doesn't compile anymore" instead.


> -----Original Message-----
> From: []
> On Behalf Of Thomas Bretz
> Sent: Thursday, July 07, 2005 4:56 AM
> To: Rene Brun
> Cc:
> Subject: Re: [ROOT] File I/O
> Hi Rene,

>>We guarantee back compatibility, ie reading files written with an old
>>version of ROOT. The inverse is more tricky. We have made an effort
>>so far to support forward compatibility. This did not happen when we
>>started version 4 (to support correctly the bool type). So you cannot
>>read files written with version 4 with older version like 3.05.
>>Could you give more details on the problems you have experienced
>>in moving to version 4?

> I get a couple of warnings about classes missing in the dictionary (they
> to me sound like new features for newer files which might not be so
> important) but for some of our classes I get warnings like "Too many
> bytes read from..." and the read contents for this classes seem to be wrong.
> Thomas.
>>On Tue, 5 Jul 2005, Thomas Bretz wrote:
>>>is there a simple way to write root-files with root 4.04/02 which are 
>>>readable with older versions (3.10/02 or 3.05/07) We have a lot of 
>>>files written with the new version, but a lot of people having 
>>>Software which doesn't work with the newer version anymore (for 
>>>several reasons).

Received on Thu Jul 07 2005 - 17:57:18 MEST

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