Disallow serializing an object directly (not through a pointer) if it doesn't have a default constructor

问题

I have recently been using save_construct_data() and load_construct_data() when I need to serialize an object without a default constructor. Since it doesn't make sense to do:

MyObject a; // can't do this because there is no default constructor
archive >> a;

we must do:

MyObject* aPointer;
archive >> a;

which calls load_construct_data() before serialize(). However, of course this only works if the object was serialized using save_constructor_data() which is only called if it is written as a pointer, e.g.

MyObject a(1,2);
MyObject aPointer = &a;
archive << aPointer;

This is all working fine, but it seems like archive << a; works fine, but logically doesn't make sense, as it will never be able to be deserialized. Is there a way to disallow this call so that objects (perhaps class members of a larger class, etc.) don't accidentally write the Object not through a pointer?

------------- EDIT ----------

Attempting to follow SergeyA's suggestion, I have made the following demo. Unfortunately it does not seem to read the data correctly?

#include <fstream>

#include <boost/archive/text_oarchive.hpp>
#include <boost/archive/text_iarchive.hpp>
#include <boost/serialization/serialization.hpp>

class Point
{
private:
    friend class boost::serialization::access;

    template<class TArchive>
    void serialize(TArchive& archive, const unsigned int version)
    {
        archive & mX;
        archive & mY;
    }

public:
    template<class TArchive>
    Point(TArchive& archive)
    {
        serialize(archive, 0);
    }

    Point(){} // Only provided to test Works()

    Point(const float x, const float y) : mX(x), mY(y) { }

    float mX = 4;
    float mY = 5;
};

void Works()
{
    std::cout << "Works():" << std::endl;
    Point p(1,2);

    std::ofstream outputStream("test.archive");
    boost::archive::text_oarchive outputArchive(outputStream);
    outputArchive << p;
    outputStream.close();

    // read from a text archive
    std::ifstream inputStream("test.archive");
    boost::archive::text_iarchive inputArchive(inputStream);
    Point pointRead;
    inputArchive >> pointRead;

    std::cout << pointRead.mX << " " << pointRead.mY << std::endl;
}

void DoesntWork()
{
    std::cout << "DoesntWork():" << std::endl;
    Point p(1,2);

    std::ofstream outputStream("test.archive");
    boost::archive::text_oarchive outputArchive(outputStream);
    outputArchive << p;
    outputStream.close();

    std::ifstream inputStream("test.archive");
    boost::archive::text_iarchive inputArchive(inputStream);
    Point pointRead(inputArchive);

    std::cout << pointRead.mX << " " << pointRead.mY << std::endl;
}

int main()
{
    Works(); // Output "1 2"
    DoesntWork(); // Output "0 0"
    return 0;
}

来源：https://stackoverflow.com/questions/35703958/disallow-serializing-an-object-directly-not-through-a-pointer-if-it-doesnt-ha

标签

c++

boost

boost-serialization