I am not actually a Boost developer, but have the following suggestion regarding boost.fusion: I find the macro BOOST_FUSION_DEFINE_STRUCT potentially very useful, but it does not provide means to influence the initialization list of the default constructor. Alternatively, means to emulate c++11 default initialization (the struct Foo {int x=10;} syntax) could be emulated. Such feature would be very useful, as it would minimize repetition and make it easier to ensure that uninitialized variables are nowhere used. I already generate my structs from BOOST_PP sequences in a similar way to BOOST_FUSION_DEFINE_STRUCT to avoid having to write json serialization boilerplate, but a variant of BOOST_FUSION_DEFINE_STRUCT i am suggesting would make this task even simpler. Pavel Bazant