Re: [Boost-users] [serialization] serializing a pointer withoutcausingobject tracking

2 Apr 2013

      I had the same problem, where I did not want a particular serialized
object to be tracked. It happened when I serialize an object that is
created on the stack and the class is usually tracked but I don't want the
instance on the stack to be tracked.

I've done a little template class that directly calls the serialize method
of the target class, and it works well...

        template<typename T>
        struct NoTracking : public T, public wrapper_traits<
NoTracking<T>,

object_class_info,
                                                             track_never,

version<T>::value >
        {
            NoTracking() : T() { }

            template<typename T0>
            NoTracking(const T0& t0) : T(t0) { }

            template<typename T0, typename T1>
            NoTracking(const T0& t0, const T1& t1) : T(t0, t1) { }

            template<typename T0, typename T1, typename T2>
            NoTracking(const T0& t0, const T1& t1, const T2& t2) : T(t0,
t1, t2) { }

            template<class Archive>
            void serialize(Archive & ar, const unsigned int version)
            {
                boostVx::serialization::serialize(ar,
static_cast<T&>(*this), version);
            }
        };

The serialize function looks like:
    void serialize(Archive & ar, unsigned int file_version)
    {
        NoTracking<Vx::VxTransform> transform = getTransform();

        ar & make_nvp("Transform", transform);

        if ( Archive::is_loading::value )
        {
           setTransform(transform);
        }
    }

--
Guy Prémont, D.Sc.
Architecte logiciel senior / Senior software architect
CM Labs Simulations Inc. http://www.cm-labs.com/
Tel. 514-287-1166 ext. 237

-----Original Message-----
From: Boost-users [mailto:boost-users-bounces@lists.boost.org] On Behalf
Of Robert Ramey
Sent: April-01-13 7:51 PM
To: boost-users@lists.boost.org
Subject: Re: [Boost-users] [serialization] serializing a pointer
withoutcausingobject tracking

Robert Ramey wrote:
...
Stefan Strasser wrote:
...
Am 30.03.2013 19:03, schrieb Robert Ramey:
...
...
is there a solution to this? is there a serialization wrapper that
says "don't track this type just because of this pointer"?
so you want "don't track this particular save - but leave others as
normal" Try something like
class A ....
class UntrackedA : public A {
...
};
BOOST_SERIALIZATION_TRACK(UntrackedA, track_never);
interesting idea. does this eventually track the object if the base
class of UntrackedA is track_selectively and saved through a pointer
anywhere else?
for example, an object graph that stores a pointer to its own root
(through intermediaries in practice):
class A{ //tracking level: selectively
  void serialize(...){ ar & a; }
  A *a; //==this
};
class UntrackedA : A{ //tracking level: never
  void serialize(...){ ar & base_object<A>(*this); } }
void save(UntrackedA *a){ ar << a; }
is "a" serialized twice, or tracked because of track_selectively and
the pointer serialization in A::serialize?
lol - I didn't think about this when I responded though I'm sure I did
it when I made the code.  I'm going to speculate since it's easier
than doing any work.
class UntrackedA : public A {
   // instead of this:
   void serialize(Archive & ar, unsigned int file_version){
       boost::serialization:base_object<A>(*this);
   }
   // consider this
   void serialize(Archive & ar, unsigned int file_version){
       ar & m_a; // where m_a is a member of a
       ar & m_b; // other member of a etc ...
   }
  ...
better yet try this:

class UntrackedA : public A {
};

just use the base class implementation of serialize function via
inheritance

Robert Ramey
...
Robert Ramey
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Re: [Boost-users] [serialization] serializing a pointer withoutcausingobject tracking

Guy Premont