Re: [Boost-users] Serialization: crash at launch of program (duetoboost::serialization::base_object)

From: RIVASSEAU Jean Noel (JN.RIVASSEAU_at_[hidden])
Date: 2006-04-06 03:53:15

I have tried to use versioning. Exact same problem.

More explanations: if I use the version facility,  and at load I switch the boost::serialization::base_object<MyBaseClass> depending on the version, the same crash will happen.

Eg: this code:

if (version == 0)
{
        boost::serialization::base_object<MyBaseClass_1>
}
Else
{
        boost::serialization::base_object<MyBaseClass_2>	
}

Will cause the same crash.

So, could you look at the code, because currently there is no way to change the base class of an object appearing in serialized archives, if you want to be able to read old archives.

It seems like there is a bug, if the base_object is used several times with different classes, the crash will appear.

Thanks

Jean-Noël

-----Message d'origine-----
De : boost-users-bounces_at_[hidden] [mailto:boost-users-bounces_at_[hidden]] De la part de Robert Ramey
Envoyé : mercredi 5 avril 2006 17:15
À : boost-users_at_[hidden]
Objet : Re: [Boost-users] Serialization: crash at launch of program (duetoboost::serialization::base_object)

The "version" facility is provided for maintaining the ability to read old 
archives.  It doesn't sound like you're using this and its sounds like you 
should be.

Robert Ramey

"RIVASSEAU Jean Noel" <JN.RIVASSEAU_at_[hidden]> wrote in message 
news:87F60F7FA02FF749AFB02BD9FCAA6B0401074928_at_naserv31.nanterre.oberthurcs.com...
Hello,

My program crashes at launch (not even a exit(0) as the first line of 
main(int argc, char *argv[]) will stop it from crashing), due to the BSL.

What I am trying to do is: I have a class, whose serialization is split (eg, 
save and load functions are provided, and they are different). Now this 
class had a parent class, so I used to call 
boost::serialization::base_object<MObject>() on the base class MObject.

However I want to change the parent of my class to a different class. I also 
want to update my old archives, so I decided to leave the load function of 
my class untouched, while I would change the save function, to update the 
call to base_object to the new parent class (not MObject anymore). I thought 
it would work, since it would load the old archive using the same method, 
but save it using the new, so I would have ran only one time the program and 
the archive would be updated (then, of course, before running it again I 
would have to recompile it one more time with the correct changes to the 
load function).

But it does not work as expected, since it seems the BSL does not like the 
fact that save and load functions calls to boost::serialization::base_object 
do not specify the same base class. It does not complain at compile time but 
crashes at run time before even entering main and certainly before loading 
any archive. The crash is due to a NULL pointer, I have tried to debug with 
gdb but the crash apparently occurs on the _libkernel32_a_iname () so I do 
not not know where it is (too low level for me).

Robert, do you have an idea what is going on? I suspect a bug - however if 
it is "normal" behaviour (I think it should then throw an exception rather 
than crash),

***
Tell that to the author of _libkernel32_a_iname ()

do you have an idea how could I update my archives? I need to change the 
parent of this class, but need to be able to read my old archives - and 
changing them "by hand" by looking into the XML archive code is tool hard.

Thank you, regards

Jean-Noël Rivasseau

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