Re: [Boost-users] Serialization bug with hash_map?

From: Chris Coleman (cqc_at_[hidden])
Date: 2005-08-11 09:17:46

Hello,

We have the same problem in our project.  The solution we have arrived 
at is:

change "boost/serialization/hash_map.hpp" as below:
//#ifdef __GLIBCPP__
#include <ext/hash_map>
//#else
//#include <hash_map>
//#endif

and add the following lines to: "boost/config/stdlib/libstdcpp3.hpp"
#define BOOST_HAS_HASH
#define BOOST_STD_EXTENSION_NAMESPACE __gnu_cxx

This has been discussed before I think, although seems still to be an 
issue in 1.33 I believe.  I think its due to the fact that there is no 
standardised hash_map map implementation.

Hope that helps,
Cheers
Chirs

Peter Lindman wrote:

>Hello, 
>
>I cannot really get the serializations to work for hash_maps. Using
>maps, lists and vectors
>everything works just fine.
>
>Using the sample code pasted below (using a hash_map) gives the
>following compilation-errors:
>
>/usr/include/boost/serialization/access.hpp: In static member function `static 
>   void boost::serialization::access::serialize(Archive&, T&, unsigned int) 
>   [with Archive = boost::archive::text_oarchive, T = __gnu_cxx::hash_map<long 
>   int, long int, __gnu_cxx::hash<long int>, std::equal_to<long int>, 
>   std::allocator<long int> >]':
>/usr/include/boost/serialization/serialization.hpp:78:   instantiated
>from `void boost::serialization::serialize(Archive&, T&, unsigned int)
>[with Archive = boost::archive::text_oarchive, T =
>__gnu_cxx::hash_map<long int, long int, __gnu_cxx::hash<long int>,
>std::equal_to<long int>, std::allocator<long int> >]'
>/usr/include/boost/serialization/serialization.hpp:121:   instantiated
>from `void boost::serialization::serialize_adl(Archive&, T&, unsigned
>int) [with Archive = boost::archive::text_oarchive, T =
>__gnu_cxx::hash_map<long int, long int, __gnu_cxx::hash<long int>,
>std::equal_to<long int>, std::allocator<long int> >]'
>/usr/include/boost/archive/detail/oserializer.hpp:148:   instantiated
>from `void boost::archive::detail::oserializer<Archive,
>T>::save_object_data(boost::archive::detail::basic_oarchive&, const
>void*) const [with Archive = boost::archive::text_oarchive, T =
>__gnu_cxx::hash_map<long int, long int, __gnu_cxx::hash<long int>,
>std::equal_to<long int>, std::allocator<long int> >]'
>/usr/include/boost/archive/detail/oserializer.hpp:243:   instantiated from here
>/usr/include/boost/serialization/access.hpp:106: error: `serialize' undeclared 
>   (first use this function)
>/usr/include/boost/serialization/access.hpp:106: error: (Each undeclared 
>   identifier is reported only once for each function it appears in.)
>
>
>Changing the created class to "busmap" (based on  std::map) everything
>works just fine!
>(The ONLY difference between the classes is the container-definition)
>
>System specs:
>
>Linux kernel version 2.4.26
>g++ (GCC) 3.3.2 20031218
>boost-1.32
>
>Sample code
>compiled with: g++ -o test test.cpp -lboost_serialization-gcc-mt
>==================================================
>
>#include <fstream>
>#include <boost/archive/text_oarchive.hpp>
>#include <boost/archive/text_iarchive.hpp>
>#include <boost/serialization/hash_map.hpp>
>#include <boost/serialization/map.hpp>
>#include <ext/hash_map>
>#include <map>
>
>class busmap
>{
>    friend class boost::serialization::access;
>    std::map<long,long> bus_serial_map; // Imaginary bus-serial-number
>to bus number lookup-table;
>    template<class Archive>
>    void serialize(Archive & ar, const unsigned int version)
>    {
>        ar & bus_serial_map;
>    }
>public:
>    busmap(){}
>};
>
>
>class bushashmap
>{
>    friend class boost::serialization::access;
>    __gnu_cxx::hash_map<long,long> bus_serial_map; // Imaginary
>bus-serial-number to bus number lookup-table;
>    template<class Archive>
>    void serialize(Archive & ar, const unsigned int version)
>    {
>        ar & bus_serial_map;
>    }
>public:
>    bushashmap(){}
>};
>
>
>int main() {
>    // create and open a character archive for output
>    std::ofstream ofs("filename");
>    boost::archive::text_oarchive oa(ofs);
>
>    // create class instance
>    const bushashmap myBusMap;
>    
>    // write class instance to archive
>    oa << myBusMap;
>    // close archive
>    ofs.close();
>
>    // ... some time later restore the class instance to its orginal state
>    // create and open an archive for input
>    
>    std::ifstream ifs("filename", std::ios::binary);
>    boost::archive::text_iarchive ia(ifs);
>    // read class state from archive
>    busmap myNewBusMap;
>    ia >> myNewBusMap;
>    // close archive
>    ifs.close();
>    return 0;
>}
>
>=======================================
>
>Bug or my fault?? Can anyone help?
>
>Best regards
>Peter
>
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>  
>

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