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copied!<p>To avoid confusion let me restate the problem.</p> <p>You want to create an object in mapped memory in such a way that after the application is closed and reopened the file can be mapped once again and object used without further deserialization.</p> <p>POD is kind of a red herring for what you are trying to do. You don't need to be binary copyable (what POD means); you need to be address-independent.</p> <p>Address-independence requires you to:</p> <ul> <li>avoid all absolute pointers.</li> <li>only use offset pointers to addresses within the mapped memory.</li> </ul> <p>There are a few correlaries that follow from these rules.</p> <ul> <li>You can't use <code>virtual</code> anything. C++ virtual functions are implemented with a hidden vtable pointer in the class instance. The vtable pointer is an absolute pointer over which you don't have any control.</li> <li>You need to be <em>very</em> careful about the other C++ objects your address-independent objects use. Basically everything in the standard library may break if you use them. Even if they don't use <code>new</code> they may use virtual functions internally, or just store the address of a pointer.</li> <li>You can't store references in the address-independent objects. Reference members are just syntactic sugar over absolute pointers.</li> </ul> <p>Inheritance is still possible but of limited usefulness since virtual is outlawed.</p> <p>Any and all constructors / destructors are fine as long as the above rules are followed.</p> <p>Even Boost.Interprocess isn't a perfect fit for what you're trying to do. Boost.Interprocess also needs to manage shared access to the objects, whereas you can assume that you're only one messing with the memory.</p> <p>In the end it may be simpler / saner to just use <a href="https://code.google.com/apis/protocolbuffers/" rel="nofollow">Google Protobufs</a> and conventional serialization.</p>

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