Re: [Boost-users] serialize explicit template instantiation

From: Reusser, Edward (Edward.Reusser_at_[hidden])
Date: 2006-11-29 18:52:21

This email was an eye popper for me because I have never had any luck
declaring a template function in a header file and defining the
implementation in a cpp file.  I either get compilation/link errors, or
very odd run-time problems.  My understanding is that many compilers (of
which mine, the MSVC 7.1 compiler) simply cannot handle this situation
at all.  I have always had to include the actual implementation of the
template function inside the header file, which is a real pain.

Note that this has nothing to do with the serialization per se.  Are
other people finding that newer compilers are finally able to handle
this?  I have several projects that I could improve by splitting the
implementation code away from the headers.

Ed

-----Original Message-----
From: Robert Ramey [mailto:ramey_at_[hidden]] 
Sent: Wednesday, November 29, 2006 8:33 AM
To: boost-users_at_[hidden]
Subject: Re: [Boost-users] serialize explicit template instantiation

I just compiled, linked and ran the following program on my system:

vc 7.1
Boost 1.35 - HEAD

There was no need to explicitly instantiate anything.

Robert Ramey

#include <boost/serialization/string.hpp>
#include <boost/serialization/base_object.hpp>
#include <boost/serialization/utility.hpp>
#include <boost/serialization/version.hpp>
class CSerTest
{
std::string a_, b_, c_;
friend class boost::serialization::access;
template<class Archive>
void serialize( Archive & ar, const unsigned int );
public:
CSerTest();
};
BOOST_CLASS_VERSION(CSerTest, 1);
// Class.cpp
#include <boost/archive/xml_oarchive.hpp>
#include <boost/archive/xml_iarchive.hpp>
CSerTest::CSerTest() : a_("1"), b_("2"), c_("3")
{
}
template<class Archive>
void CSerTest::serialize( Archive & ar, const unsigned int )
{
ar & BOOST_SERIALIZATION_NVP(a_) & BOOST_SERIALIZATION_NVP(b_) & 
BOOST_SERIALIZATION_NVP(c_);
}
// main.cpp
#include <fstream>
///////////////////////// without effect 
////////////////////////////////////
//template void 
CSerTest::serialize<boost::archive::xml_oarchive>(boost::archive::xml_oa
rchive&, 
unsigned int );
int main()
{
const CSerTest instance;
std::ofstream ofs( "out_file.txt" );
boost::archive::xml_oarchive oxa( ofs );
oxa << BOOST_SERIALIZATION_NVP(instance);
} 

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