deal with boost variant and boost function - c++

Question

I would like a vector to hold differents kind of boost::function, so, I tried a variant :
#include <boost/variant.hpp>
#include <boost/bind.hpp>
#include <boost/function.hpp>
#include <vector>
void a(int, int)
{}
void b()
{}
int main(int argc, char **argv)
{
typedef boost::variant<boost::function0<void>, boost::function2<void, int, int>> v;
std::vector<v> c;
c.push_back(boost::bind(&a, _1, _2));
c.push_back(boost::bind(&b));
auto& function = boost::get<boost::function2<void, int, int>>(c[0]);
function(4, 5);
}
But I've this error :
/usr/local/include/boost/variant/variant.hpp:1515:28: error: call to member function 'initialize' is ambiguous
initializer::initialize(
~~~~~~~~~~~~~^~~~~~~~~~
/usr/local/include/boost/variant/variant.hpp:1692:9: note: in instantiation of function template specialization 'boost::variant<boost::function0<void>, boost::function2<void, int, int>, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_>::convert_construct<boost::_bi::bind_t<void, void (*)(int, int), boost::_bi::list2<boost::arg<1>, boost::arg<2> > > >' requested here
convert_construct( detail::variant::move(operand), 1L);
^
I didn't find any help to deal with theses error
(and other compiler output)
https://ideone.com/QEdlyF
Thanks !

Answer 1

The constructor for Boost Function is pretty liberal in what it can accept. This results in there being no "best" constructor amongst the elements types of the variant.
You'll have to explicitly cast.
Then again, it's probably even easier to just hide the knowledge about types alltogether (since the helpful parts are ambiguous anyways) and use Boost Any.