Re: [Boost-users] Boost::Serialization and MFC Doc/View architecture

3 Jul 2011

      I hope you don't mind, but I've a bit more information on this:

Reading the documentation closer, I see that Boost acknowledges that any
serialized pointer is deserialized with a new keyword: "Serialization of
pointers is implemented in the library with code similar to the following:"

// load data required for construction and invoke constructor in place
template<class Archive, class T>
inline void load_construct_data(
Archive & ar, T * t, const unsigned int file_version
){
// default just uses the default constructor to initialize
// previously allocated memory.
::new(t)T();
}

The documentation recommends overloading this function if necessary:

template<class Archive>
inline void load_construct_data(
Archive & ar, my_class * t, const unsigned int file_version
){
// retrieve data from archive required to construct new instance
int attribute;
ar >> attribute;
// invoke inplace constructor to initialize instance of my_class
::new(t)my_class(attribute);
}

But this would again result in needed to implement a CMyDoc copy
constructor.

Any help very much appreciated - thank you.
Colin

On Sun, Jul 3, 2011 at 1:31 AM, Colin Caprani <cc.caprani@gmail.com> wrote:
...
Hi All,
I'm porting an existing MFC C++ application to use Boost::Serialization for
XML files. My CDocument object contains all the data for the app. I've
implemented the serialize function as:
template<class Archive>
    void CMyDoc::serialize(Archive& ar, const unsigned int version)
    {
    ar    & BOOST_SERIALIZATION_NVP(m_Param1)
        & BOOST_SERIALIZATION_NVP(m_Param2);
    }
To capture the save and load events, in the CMyDoc.cpp file I have:
BOOL CMyDoc::OnOpenDocument(LPCTSTR lpszPathName)
    {
    clear();    // clear current params
//if (!CDocument::OnOpenDocument(lpszPathName)) // Old MFC serialize
code
    //    return FALSE;
CEvolveTrafficDoc* pDoc = this; // pointers the same here
    std::ifstream ifs(lpszPathName);
    boost::archive::xml_iarchive ia(ifs);
    ia >> boost::serialization::make_nvp("MyDoc",pDoc); // pointer changes
here
return TRUE;
    }
BOOL CMyDoc::OnSaveDocument(LPCTSTR lpszPathName)
    {
    //if (!CDocument::OnSaveDocument(lpszPathName)) // Old MFC serialize
code
    //    return FALSE;
std::ofstream ofs(lpszPathName);
    boost::archive::xml_oarchive oa(ofs);
    oa << boost::serialization::make_nvp("MyDoc",this);
return TRUE;
    }
Saving a document works fine. The problem is that loading a document
doesn't work. The boost library seems to copy the CMyDoc object because the
pointer comes back a different address. This means that the loaded file
isn't loaded into the current document. Can a CDoc overwrite itself with
boost? It can with MFC CArchive.
If I overload the CMyView to capture the file open and save events, the MRU
list management offered by the Doc/View architecture won't happen.
I'm sure this has been done a million times, but I can't find any
information online. Weird! Any help much appreciated.
Thanks,
Colin