Re: ClassDef version

Rene Brun (Rene.Brun@cern.ch)
Thu, 01 Jul 1999 12:47:24 +0000

Olivier Meplan wrote:
>
> Hi rooters!
>
> I have a question about increasing the id of ClassDef ; I add members to
> a existing class
> but I want to be able to read older objects of this class. I understood
> that I have to modify the streamer function to take that into account in
> the Dictonary file. I have done that and all seems to work but is there
> a way to do that automatically (because in the make file I use, the
> dictonary file is automatically generated without the modification
> if(R__v>1){...}?
> Thanks a lot
> Olivier Meplan

Hi Olivier,
By definition, this process cannot be automatized.
You should follow the following steps:
- Increase class version in ClassDef
- Take a copy of your old Streamer in the dictionary and add this
function in your class implementation.
- Modify your Linkdef.h file to add the symbol "-" after the class
name
This instructs rootcint to not generate the Streamer function.
- run rootcint with the new Linkdef.

For more info, see URL:

http://root.cern.ch/root/RootCintMan.html

Rene Brun