Re: [Boost-users] Serialization: Visual C+ Template Bug ?

From: Oliver Kania (kania.oliver_at_[hidden])
Date: 2007-11-30 05:02:57

Sry but I do not understand. I do specify the implementation with

template<class Archive>
        void PaloClient::serialize( Archive &ar, const unsigned int version
) {
            ar & m_PaloClientImpl;
        }

as you suggest and as I have written in example 1.
Then I write

template void PaloClient::serialize<boost::archive::text_iarchive>(
            boost::archive::text_iarchive & ar,
            const unsigned int file_version
            );

        template void PaloClient::serialize<boost::archive::text_oarchive>(
            boost::archive::text_oarchive & ar,
            const unsigned int file_version
            );

to make the compiler generate code for these two template parameters.
It works for me in other cases and it is what the documentation says.
I dont think that removing the two template-specification could solve the
issue,
since the template function-definition is not included in any header file.
There must be some misunderstanding.

Kind regards, Oliver

On Nov 29, 2007 5:27 PM, Robert Ramey <ramey_at_[hidden]> wrote:

>  This is a C++ syntax issue.
>
> The first example explicitly instantiates the serialize declaration
> without specifying its implementation
> which leads to an undefined symbol. just use:
>
> template<class Archive>
>         void PaloClient::serialize( Archive &ar, const unsigned int
> version ) {
>             ar & m_PaloClientImpl;
>         }
>
> and the appropriate code wil be instantiated if and only if it is actually
> invoked.
>
> Robert Ramey
>
>
>
> "Oliver Kania" <kania.oliver_at_[hidden]> wrote in message
> news:1262c4ee0711290739x12408875u39e54bbe9effb093_at_mail.gmail.com...
> Hello !
>
> When linking a program that consists only of main.cpp with a library that
> serializes
> a class "Palo Cllient"  I get the  following message (sry for the mess):
>
> ==================================================
>  error LNK2019: unresolved external symbol "private: void __thiscall
> jedox::palo::PaloClient::serialize<class
> boost::archive::text_oarchive>(class boost::archive::text_oarchive
> &,unsigned int)" (??$serialize@ Vtext_oarchive_at_archive@boost@@@
> PaloClient_at_palo@jedox@@AAEXAAVtext_oarchive_at_archive@boost@@I_at_Z) referenced
> in function "public: static void __cdecl
> boost::serialization::access::serialize<class
> boost::archive::text_oarchive,class jedox::palo::PaloClient>(class
> boost::archive::text_oarchive &,class jedox::palo::PaloClient &,unsigned
> int)" (??$serialize@ Vtext_oarchive_at_archive@boost@@VPaloClient_at_palo
> @jedox@@@access_at_serialization@boost@@SAXAAVtext_oarchive_at_archive@
> 2_at_AAVPaloClient@palo_at_jedox@@I_at_Z)
> ==================================================
>
> This happens even though I do NOT explicitly serialize anything.
> Main.cpp includes:
>
> #include <boost/archive/text_oarchive.hpp>
> #include <boost/archive/text_iarchive.hpp>
>
> For the class PaloClient, I do use the Pimpl idiom and serialize as it is
> recommended
> in the documentation:
>
> PaloClient.cpp:
>
> --------------------------------------------------------------
>
> #include <boost/archive/text_oarchive.hpp>
> #include <boost/archive/text_iarchive.hpp>
> #include <boost/serialization/scoped_ptr.hpp>
>
> ....
>
> template<class Archive>
>         void PaloClient::serialize( Archive &ar, const unsigned int
> version ) {
>             ar & m_PaloClientImpl;
>         }
>
> template void PaloClient::serialize<boost::archive::text_iarchive>(
>             boost::archive::text_iarchive & ar,
>             const unsigned int file_version
>             );
>
>         template void
> PaloClient::serialize<boost::archive::text_oarchive>(
>             boost::archive::text_oarchive & ar,
>             const unsigned int file_version
>             );
> ------------------------------------------------------------------------
>
> Now, when I change this to
>
>
>         void PaloClient::serialize(boost::archive::text_iarchive & ar,
> const unsigned int file_version) {
>             ar & m_PaloClientImpl;
>         }
>
>         void PaloClient::serialize (boost::archive::text_oarchive & ar,
> const unsigned int file_version) {
>                 ar & m_PaloClientImpl;
>         }
>
> The linkage error disappears. I guess this is a Visual C++ compiler
> problem but
> I wanted to post this in case someone else has similar problems.
>
> Kind regards, Oliver
>
> PS: Thanks for this great serialization library, it saved me many weeks of
> programming.
>
>
>  ------------------------------
>
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