Try deriving form text_iarchive_impl. Note that a comment in text_iarchive.hpp explicitly states that it shouldn't be derived from. For an example on how to derive from an existing archive look at demo_fast_archive and review the section of the manual which discusses this topic.
Robert Ramey
"Haskins, Gregory" wrote in message news:5CFCA4B6F572E74384A26FBA61CAE837018A5D34@MAANDMBX1.ets.enterasys.com...
I posted this earlier, but I don't think it went through all the way. I apologize if this is a duplicate:
--------------------------------------------------------------------------------------------
Hi All,
Boost newbie here: I am having problems with getting serialization to work
with my app. I have a top-level "environment" context that objects in my app
need to be associated with. I thought about various ways to accomplish this
and I thought the best way might be to derive an Archive class that maintains a
reference to the context and use custom save_construct_data/load_construct_data
overrides.
However, I am hitting a snag and I don't quite understand what is happening. I
derive an input and output archive from text_iarchive/text_oarchive
respectively and I use this archive context. However I get the following
error in compilation:
db.hh: In function `void boost::serialization::load_construct_data(Archive&,
FlatFileDb::Db*, unsigned int) [with Archive =
boost::archive::text_iarchive]':
/ccase/cca/vendor/boost/boost/serialization/serialization.hpp:170:
instantiated from `void boost::serialization::load_construct_data_adl(Archive&,
T*, unsigned int)
[with Archive = boost::archive::text_iarchive, T = FlatFileDb::Db]'
/ccase/cca/vendor/boost/boost/archive/detail/iserializer.hpp:303: instantiated
from `void boost::archive::detail::pointer_iserializer::load_object_ptr(boost::archive::detail::basic_iarchive&, void*&,
unsigned int) const [with T = FlatFileDb::Db, Archive =
boost::archive::text_iarchive]'
/ccase/cca/vendor/boost/boost/archive/detail/iserializer.hpp:209:
instantiated from here
db.hh:84: error: 'class boost::archive::text_iarchive' has no member named '
m_env'
Somehow the system is assigning <class Archive> to 'class
boost::archive::text_iarchive' even though I am creating the archive as
something derived from text_iarchive. The weird thing is that this happens
even if I comment out the code the invokes the actual archiving. Its almost
like there is some default value of Archive that gets assigned once I include
the text_iarchive.hpp file. Any ideas on how to stop this from happening?
Is there a better way to accomplish my goal?
Thanks in advance!
-Greg
PS: Here are some code snippets of what I am doing.
I have a header file called "archive.hh" with
-----------------------------------------------------------
#include
#include
namespace FlatFileDb
{
class Env;
class OArchive : public boost::archive::text_oarchive_impl<OArchive>
{
public:
OArchive(Env &env, std::ostream & os, unsigned int flags = 0) :
boost::archive::text_oarchive_impl<OArchive>(os, flags), m_env(env)
{}
~OArchive(){}
Env &m_env;
};
class IArchive : public boost::archive::text_iarchive_impl<IArchive>
{
public:
IArchive(Env &env, std::istream & is, unsigned int flags = 0) :
boost::archive::text_iarchive_impl<IArchive>(is, flags), m_env(env)
{}
~IArchive(){}
Env &m_env;
};
};
--------------------------------------------------
and then I have another header file (db.hh) with:
--------------------------------------------------
<.../snip...>
namespace boost { namespace serialization {
template<class Archive>
inline void save_construct_data(
Archive & ar, const FlatFileDb::Db *t, const unsigned int file_version
){
// save data required to construct instance
ar << t->m_name;
}
template<class Archive>
inline void load_construct_data(
Archive & ar, FlatFileDb::Db* t, const unsigned int file_version
){
// retrieve data from archive required to construct new instance
std::string name;
ar >> name;
// invoke inplace constructor to initialize instance of my_class
::new(t)FlatFileDb::Db(ar.m_env, name); <-- !!! blows up here !!!y
}
}} // namespace ...
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