Hello Robert, Just to let you know that everything works fine now. Thanks for your help, Guy -----Original Message----- From: boost-users-bounces@lists.boost.org [mailto:boost-users-bounces@lists.boost.org] On Behalf Of Robert Ramey Sent: Monday, August 07, 2006 1:18 PM To: boost-users@lists.boost.org Subject: Re: [Boost-users] [Serialization] Problem serializingviabaseclassptr Guy Létourneau wrote:

Hello Robert,

Sorry for not giving you feedback earlier, I was on vacation. I've included your proposed changes in my test application but I still get the same compile error:

C:/Boost/include/boost-1_33_1/boost/archive/detail/oserializer.hpp: In function `void boost::archive::save(Archive&, T&) [with Archive = boost::archive::text_oarchive, T = const A*]': C:/Boost/include/boost-1_33_1/boost/archive/basic_text_oarchive.hpp:78: instantiated from `void boost::archive::basic_text_oarchive<Archive>::save_override(T&, int) [with T = const A*, Archive = boost::archive::text_oarchive]' C:/Boost/include/boost-1_33_1/boost/archive/detail/interface_oarchive.hpp:78: instantiated from `Archive& boost::archive::detail::interface_oarchive<Archive>::operator<<(T&) [with T = const A*, Archive = boost::archive::text_oarchive]' ../main.cpp:101: instantiated from here C:/Boost/include/boost-1_33_1/boost/archive/detail/oserializer.hpp:567: error: incomplete type `boost::STATIC_ASSERTION_FAILURE<false>' does not have member `value' make: *** [main.o] Error 1

Could you tell me what I'm missing?

Thanks again for your help,

Guy Letourneau

Test application:

#include <iostream> #include <fstream>

#include #include #include

class A { public:

A() { i = 1; };

virtual ~A() { };

virtual void Dummy() = 0;

private:

int i;

friend class boost::serialization::access;

template <class Archive> void serialize( Archive& ar, const unsigned int version ) { std::cout << "Serialization of A" << std::endl; std::cout.flush(); } }; BOOST_IS_ABSTRACT(A)

class B : public A { public:

B() { };

virtual ~B() { };

void Dummy() { };

void SetValue( std::string& value ) { Data = value; }

private:

friend class boost::serialization::access;

template <class Archive> void serialize( Archive& ar, const unsigned int version ) { ar & boost::serialization::base_object<A>( *this ); ar & Data; std::cout << "Serialization of B" << std::endl; std::cout.flush(); }

std::string Data; }; BOOST_CLASS_EXPORT(B)

int main() { // Create a B object B* Child = new B;

// Set some data std::string Data = "test"; Child->SetValue( Data );

// Assign it to a A ptr

**** // > const A* Parent = Child; // Parent is now const // nope- Parent is not const - it points to a const A - not the same thing !!! // try const A * const Parent = Child; // const pointer to a const A // also the following will work - I believe A * const Parent = Child;

// create and open a character archive for output std::ofstream ofs( "filename" );

// save data to archive { try { boost::archive::text_oarchive oa( ofs ); // write class instance to archive oa << Parent; // Ptr dereferencing is performed by the library } catch( boost::archive::archive_exception& e ) { std::cout << "Save failed! : " << e.what(); std::cout.flush();

return false; } catch( ... ) { std::cerr << "Unknown Exception " << std::endl;

return false; }

// archive and stream closed when destructors are called }

delete Child; }

-----Original Message----- From: boost-users-bounces@lists.boost.org [mailto:boost-users-bounces@lists.boost.org] On Behalf Of Robert Ramey Sent: Saturday, July 22, 2006 6:43 PM To: boost-users@lists.boost.org Subject: Re: [Boost-users] [Serialization] Problem serializingviabaseclassptr

Three show stopping problems in this code:

a) A doesn't have serialize method even though such a method is invoked by base object. see: http://www.boost.org/libs/serialization/doc/serialization.html

b) saving a non-const object - see rationale section

c) Main show stopper:

...

int main() { // Create a B object B* Child = new B;

// Set some data std::string Data = "test"; Child->SetValue( Data );

// Assign it to a A ptr // const A* Parent = Child; // ****** note new const - see rationale

// create and open a character archive for output std::ofstream ofs( "filename" );

// save data to archive { try { boost::archive::text_oarchive oa( ofs ); // write class instance to archive // *** big problem here. Dereferecing pointer to A yields a ref // *** to an A - regardless that ptr was a B. What you really want is: oa << Parent; // *** let serialization handle dererencing // *** instead of: //oa << *Parent; } catch( boost::archive::archive_exception& e ) { std::cout << "Save failed! : " << e.what(); std::cout.flush();

return false; } catch( ... ) { std::cerr << "Unknown Exception " << std::endl;

return false; }

// archive and stream closed when destructors are called }

delete Child; }

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