Re: [boost] [serialization] Must the objects being serializedoutlive the archive?

Subject: Re: [boost] [serialization] Must the objects being serializedoutlive the archive?
From: Jeff Flinn (TriumphSprint2000_at_[hidden])
Date: 2010-09-18 16:13:52

Robert Ramey wrote:
> Chris Yuen wrote:
>> Jeff Flinn wrote:
>>
>>> IIUC, tracked objects have their addresses place in a map, so that
>>> subsequent serialized pointers of the same value are serialized as a
>>> reference to the original object at that address, rather than
>>> serializing another copy of the object.
>> That was spot on! I did a couple of tests and I think I've confirmed
>> this is indeed the behavior
> 
> It's also described in the documentation under "tracking"

Perhaps it could be described in a clearer fashion? What text are you 
explicitly referring too? I just scanned Reference/Serializable 
Concept/Pointers/Pointers to Objects of Derived Classes. I don't see any 
explicit description of the requirements imposed by tracking.

>>  and the reason why data gets corrupt. On
>> my platform (MSVC), new data gets allocated to the last free
>> pointer's address and that confuses boost::serialization.
> 
> This is only a problem because you delete the data while it's being
> serialized.
> 
>>> From your understanding, doesn't that basically means the "objects
>>> being
>> serialized must outlive the archive"? Since there's no way to tell
>> "new" to not allocate objects at an older address unless I keep
>> objects there. So basically I must keep all data in memory until the
>> serialization process is complete.

This statement is correct for tracked objects serialized by pointer.

>> I tried to think hard about this. Do you see any workaround to this
>> issue so that I don't have to effectively double the memory usage?
> 
> I don't see any doubling of memory usage here.

Paraphrasing Chris: when properly serializing N Base instances to a 
single archive, all N Base instances must reside in memory 
simultaneously. What Chris's trying to do is serialize N Base instances 
only allocating memory for one Base instance at a time.

>> (Maybe have boost::serialization write things out immediately and
>> clear the internal cached pointers)? Maybe boost::serialization
>> should provide that command or some kind of "flush" command?
> 
> Maybe you don't want to serialize via a pointer.  Just serialize the
> data itself.  Then there is nothing to allocate/deallocate, etc.
 >
> If you're having to go to such trouble, you must be doing something
> fundamentally wrong.

I haven't tried [de]serializing through a ref to base class, can that be 
done?

Jeff