New subject: [multi_index] announce: serialization support

2 Dec 2004

      ----- Mensaje original -----
De: Robert Ramey <ramey@rrsd.com>
Fecha: Jueves, Diciembre 2, 2004 0:36 am
Asunto: [boost] Re: Re: Re: [multi_index] announce: serialization 
support
...
"JOAQUIN LOPEZ MU?Z" <joaquin@tid.es> wrote in message
news:206712203b1d.203b1d206712@tid.es...
...
----- Mensaje original -----
De: Robert Ramey <ramey@rrsd.com>
Fecha: Miércoles, Diciembre 1, 2004 10:15 pm
Asunto: [boost] Re: Re: [multi_index] announce: serialization 
support
[snip]
...
...
If you guarentee that the container itself is always serialized
before your
indices, then de-serialization of the indices would automatically
be reduced
to providing the original (tracked) pointer.  In such a case, I
would think
the whole isse would never appear and that the implementation
would be very
straight forward.
...
I think this is not correct (but I'd like to be
proven wrong, that'd mean I could simplify my code.)
Consider this:
...
struct foo
{
  std::list<std::string> cont;
  std::string*           pos; // pos points to an element of cont
...
private:
  friend class boost::serialization::access;
...
template<class Archive>
  void serialize(Archive & ar, const unsigned int)
  {
    ar&cont; // before pos, as you suggest
    ar&pos;
  }
};
...
My thesis is that loading a foo will get it
wrong --pos won't be pointing to an element of cont,
but rather to some random address in stack memory.
I'll check it out on my compiler tomorrow, but I was
already through this when designing multi_index
serialization. See my point now? Am I missing something?
Hmmm - let me consider this.  My view is based on the test 
test_list_ptrwhich serializes a list of pointers. In this case 
each list element is
tracked because its a pointer.   when a pointer is de-serialized a 
secondtime, tracking assures that the pointer is reloaded.
In your case - std::string is tracked on output.  When it its 
serialized a
second time, only the object ID is written out.  So when it is 
read back in
the second time, the serialization system recognizes that its a 
copy and
just reloads it.
This only gotcha is that most primitive types are not tracked by 
default.and std::string has been assigned a serialization trait of 
"primitive" that
means don't track.  So I believe that this would work for non-
primitivetypes.
Oh, I choose std::string cause I thought it was tracked
by default, my point was meant to hold for trackable
types. So, replace std::string wit the user-defined type of
your choice and I still maintain that serialization of
foo will go wrong.

So that we don't keep discussing on thin air, please
allow me to get back to you tomorrow with a complete,
compiled example of what I mean. If in the meantime
you do the check yourself please tell me what you
come up with.

Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo

Re: [boost] Re: Re: Re: [multi_index] announce: serialization support

JOAQUIN LOPEZ MU?Z

Robert Ramey

Joaquín Mª López Muñoz

Robert Ramey

Joaquín Mª López Muñoz

Robert Ramey

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