[Boost-users] variant within a recursive_variant?

Subject: [Boost-users] variant within a recursive_variant?
From: Matthew L. Creech (mlcreech_at_[hidden])
Date: 2009-06-27 18:49:11

Hi,

I'm wondering if anyone has successfully embedded a boost::variant<>
within a recursive variant.  The program below illustrates what I'm
trying to do:

=============
#include <vector>
#include <string>
#include <boost/variant.hpp>

typedef boost::variant<
                       double,
                       std::string
                       > a_t;

struct b_t { };

typedef boost::make_recursive_variant<
                                      a_t,
                                      b_t,
                                      std::vector<boost::recursive_variant_>
                                      >::type c_t;

int main()
{
        a_t a(20.0);
        c_t c(a);
        return 0;
}
=============

With GCC, this gives me:

...
boost/variant/variant.hpp:1269: error: no matching function for call
to 'boost::detail::variant::initializer_root::initialize(void*,
double&)'

Normal variant-within-a-variant works fine (i.e. if I remove the
vector, and just declare c_t without make_recursive_variant<>).  And
make_recursive_variant<> with plain types works as well (i.e. if a_t
is a non-variant type).  But I can't figure out how to make the two
work together...

Any help would be greatly appreciated.  Thanks!

-- 
Matthew L. Creech