###

# Serialization

## Release Notes

Differences from version 1.45
Differences from version 1.43
Differences from version 1.42
Differences from version 1.41
Differences from version 1.40
Differences from version 1.39
Differences from version 1.37
Differences from version 1.35
Differences from version 1.34
Differences from version 1.33
Differences from version 1.32
Pending Issues

As of this writing, there are no known bugs. However, due to compiler/library quirks and or bugs, some tests fail with some combinations of compilers and libraries.

## Differences from Boost 1.45

Since the release of version 1.42, it has been discovered that binary archives created by versions 1.42-1.44 cannot always be read by the recent binary archive code. Work has proceeded in detecting the source of these anomolies and those which have been reported with test cases have been fixed. As of this writing, it is not known whether all binary archives created with these versions can be loaded.

## Differences from Boost 1.43

- fixed bug in the serialization of virtual base classes. Due to heroic efforts by Takatoshi Kondo.
- Native binary archives created under versions 1.42 and 1.43 suffer from a serious problem. It's likely they won't be readable by this latest version. This due to the fact that 1.42 made some changes in the binary format of some types. Normally this could be addressed by detecting the library version number written into the archive header. Unfortunately, this library version number was not incremented at 1.42 as it should have been. So now we have two different binary archive versions with the same library version number.

  This has been addressed by including a small utility in the example directory named fix_six.cpp. This should be run with the command line
  ``

          fix_six <file name>

  This will assign 7 to the library version number of the archive. This fix will need to ba applied to native binary archives created with boost versions 1.42 and 1.43.

## Differences from Boost 1.42

- fixed failure of shared_ptr serialization when serializing pointers created from enable_shared_from_this.
- added example for a simple archive which can be used as a debug log. This example illustrates the implemenation of the archive concept to aid understanding required to create one's own archive classes. The resulting archive is useful for debugging in that it only 160 lines of code and is header only - that is, it doesn't required linking to the serialization library.
- replaced example used to show how to derive from an existing archive. This example creates an XML archive class which doesn't include serialization traits such as class_id, class_version, etc. It might be useful for exporting one's class information to osme XML processor and/or debugging programs.
- compile time warnings have been implemented to detect practices which though correct, will result in operation or side effects different than a user probably intends.
- Some memory leaks associated with void_cast have been fixed.

## Differences from Boost 1.41

- adjustments have been made to minimize compile time warnings.
- compile time warnings have been implemented to detect practices which though correct, will result in operation or side effects different than a user probably intends.
- Some memory leaks associated with void_cast have been fixed.

## Differences from Boost 1.40

This library has been tested against Boost version 1.39 and 1.40.

Changes have been made to archive classes included with the library. Users who have used these a guide to making their own archive classes will find that these will likely no longer compile. This can be remedied by making the following changes in the code which instantiates these archive classes.

Old Code:
`

    ...
    #include <boost/archive/impl/archive_pointer_iserializer.ipp>
    ...
    template class detail::archive_pointer_iserializer<naked_text_iarchive> ;
    ...
    template class detail::archive_pointer_iserializer<text_iarchive> ;

`should be replaced with this new code: `

    #include <boost/archive/impl/archive_serializer_map.ipp>
    ...
    template class detail::archive_serializer_map<naked_text_iarchive> ;
    ...
    template class detail::archive_serializer_map<text_iarchive> ;

`

## Differences from Boost 1.39

- It is now possible to serialize an object through a pointer to a class which implements its own `new/delete` operators. This functionaly is not available on some compilers.
- serialization of polymorphic objects has been sped up considerably.

As of this writing, all bug reports filed as TRAK tickets have been addressed. There are some TRAK tickets pending which would best be described as feature requests. See Pending Issues.

## Differences from Boost 1.37

There are no new features in this version. As of this writing, all bug reports filed as TRAK tickets have been addressed. There are some TRAK tickets pending which would best be described as feature requests. See Pending Issues.

## Differences from Boost 1.36

There are no new features in this version. As of this writing, all bug reports filed as TRAK tickets have been addressed.

## Differences from Boost 1.35

- The library is now thread safe. That is, multiple archives can be open in different threads. This has been implmented with a lock-free algorithm to avoid any performance bottlenecks.
- Serialization of types defined in shared libraries is now supported. shared libraries (DLLS) can be loaded/unloaded dynamically at runtime. This includes the serialization of instances of abstract base classes so that a program can be written so as to be compatible with as yet undefined and un-implemented code.
- The extended type info system has been enhanced to in order to implement the above. It is now a general purpose system for creating and casting of types about which is only known a string ID and an abstract base class.
- All bug reports filed as TRAK tickets have been addressed.
- As of this writing, the library will fail build on older compilers such as MSVC before version 7.1 and older versions of Borland compilers. This might or might not change in the future.

## Differences from Boost 1.34

- Enhanced support for fast serialization for native binary archives. By Mattias Troyer.
- Improved implementation of "export" functionality. Removes header ordering requirement and eliminates the maintenance of a pre-determined list of "known archives" By David Abrahams.
- Improved support for STLPort.

## Differences from Boost 1.33

- Native Binary archives use the `std::streambuf` interface. This should result in noticeably faster execution in many cases.

## Differences from Boost 1.32

- Dynamic Linking Library (DLLs and shared libraries) for platforms which support them. See Automatic Linking on Windows.
- Implementation of auto-link for compilers which can support this.
- Better support for Argument Dependent Lookup and two-phase lookup. This results in simpler rules regarding the placing of serialization specializations namespaces.
- Enhanced documentation to help explain usage of the above.
- Adjustments to improve support for less conformant compilers.
- Improved `const` correctness for save/load operators. Note that this may produce compile time errors in code which compiled without problem in earlier boost releases. In most cases the fix is trivial. In other cases, code should be scrutinized to be sure that it doesn't use the serialization system in a way which may introduce subtle bugs in to the program. A fuller explanation of this issue can be found here.
- A new implementation of serialization for `shared_ptr<T>`. This is compatible with public interface of `shared_ptr<T>` so it should be more robust and not have to change in the future. The implementation optionally includes code to load `shared_ptr<T>` stored in archives created with boost 1.32. This code is stored in 'he header: `boost/serialization/shared_ptr_132.hpp`. If your application needs to load archives created with boost 1.32 libraries, include the above header before each inclusion of `boost/serialization/shared_ptr.hpp`.
- More compilers tested and supported.
- Miscellaneous bug fixes.

## Pending issues

- Rvalues cannot be serialized. It would be possible to implement this for untracked types, but this has not been done.
- Pointers to pointers cannot currently be serialized
- It's possible that `std::string` and `std::wstring` contain characters such as '\0' and -1 (EOF) which cannot be rendered in text and XML archives without an escape mechanism. Currently there is no such escape mechanism implemented.
- A subtle error in the implementation of serializaton of `std::map` is fixed in this version. Unfortunately, the fix breaks serialization of `std::map` for those compilers which do not support partial template specialization. Also, types which contain pointers or tracked types might not work correctly.
- Serialization of virtual base classes relies upon RTTI. It will fail when used on systems which don't have RTTI enabled.

Aside from the above, there are a number of issues related to specific platforms. These are listed in Specific Compiler/Library Issues.

© Copyright Robert Ramey 2002-2009. Distributed under the Boost Software License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)