Re: [Boost-users] Recursive variant problem

Subject: Re: [Boost-users] Recursive variant problem
From: Larry Evans (cppljevans_at_[hidden])
Date: 2010-07-07 13:53:08

On 07/07/10 09:53, Timothy Madden wrote:
> Hi
> 
> I use the following type in my application:
> 
> boost::make_recursive_variant
>     <
>     boost::tuple
>         <
>         std::basic_string<TCHAR>,            // id
>         std::basic_string<TCHAR>,            // name
>         std::basic_string<TCHAR>,            // desc
>         std::basic_string<TCHAR>,            // type
>         std::basic_string<TCHAR>,            // value
>         std::vector<boost::recursive_variant_>        // childList
>         >
>     >::type
> 
> However when I instantiate it and I try to populate (resize) the vector 
> (member indexed 5 in the tuple, childList) I get:
>      'boost::recursive_variant_' : class has no constructors
> from Visual Studio 2008 SP1.
> 
> It looks like the boost::recursive_variant_ type is not substituted with 
>  the type of the enclosing variant by the make_recursive_variant 
> meta-function. Am I missing something ? Is this is bug ?
> 
> I have also tried adding some more members to the variant, with no success.
> 
> Thank you,
> Timothy Madden
Maybe you could just use pointers to the enclosing composite, like in:

#include <tr1/tuple>
#include <vector>

struct tuple_tree
: std::tr1::tuple
   < float
   , int
   , std::vector<tuple_tree*>
   >
{
};

int main(void)
{
     tuple_tree tt;
     std::vector<tuple_tree*>&children=std::tr1::get<2>(tt);
     children.push_back(new tuple_tree);
     return std::tr1::get<1>(tt);
}