Ten Points Random

Using shared_from_this inside boost::serialization

by on Dec.01, 2012 @ 06:13 pm, under Programming

Didn’t find a solution foe this on the Internet, so I thought I’d just write this up real quick to benefit anyone that was having the same issue.

If you are using boost::serialization and shared_ptr, you may have already discovered that all you have to do is add

#include <boost/serialization/shared_ptr.hpp>

to make them work together happily.

However, if your initialization routine inside your load requires shared_from_this, you may find yourself getting

terminate called after throwing an instance of 'boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<boost::bad_weak_ptr> >'
  what():  tr1::bad_weak_ptr

when trying to call methods that require shared_from_this in s11n code.

This happens because a sahred_ptr hasn’t been created for yoru unserializing class yet. To work around this, define this macro:

//Extra to make shared_from_this available inside the saving code
//This works by asking the archive to handle (and therefore create) a shared_ptr for the data
//before the main serialization code runs.
#define ALLOW_SHARED_THIS(type) \
    template<class Archive> inline void load_construct_data(Archive &ar, type *obj, const unsigned int file_version) { \
        boost::shared_ptr<type> sharedPtr; \
        ::new(obj)type();/* create instance */ \
        ar.reset(sharedPtr, obj); /* Tell the archive to start managing a shared_ptr */ \

Then use it for each class that needs the shared_from_this functionality:

namespace boost { namespace serialization {

This defines a custom constructor for your class that will create the shared_ptr for your instance before your main s11n code runs and allow your code to run peacefully.


1 comment for this entry:
  1. Eric Raijmakers

    Hi Jon,

    Just wanted to let you know that your post on ‘shared_from_this icw boost::serialization’ really helped me a lot today!

    There’s one thing that took me some time to figure out today so I I’ll mention it here: if (de)serializing a derived class, be sure to use ‘load_construct_data’ on the derived class, and not on the base class….

    In hindsight, it’s pretty obvious. Still it took me quite some time to discover.

    Again, thanks for your post!


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