[boost] Re: problems with binary variant visitors in 1.31

6 Feb 2004


      Never mind. Sorry I didn't notice 'const' in data().
Everything is pefect now.

Eugene


--- "E. Gladyshev" <egladysh@yahoo.com> wrote:
...
Great job with the 1.31 release!
Just wondering if anybody else observerved this kind of problems before.
When compiling the code below with MSVC 7.1, I am getting this error:
test.cpp(123) : error C2039: 'set' : is not a member of 'my_type::test1'.  
GCC 3.2.3 gives a compilation error as well.
template< typename T >
struct binary_variant_visitor : public ::boost::static_visitor<>
{
    T& obj_;
binary_variant_visitor( T& obj ) : obj_(obj) {}
template< typename VT1, typename VT2 >
    void operator()( VT1& v1, VT2& v2 )
    {
        obj_.visit( v1, v2 );
    }
};
struct my_type
{
    struct test1
    {
        test1();
        ~test1();
    };
    struct test2
    {
        ~test2();
        template< typename T >
        void set( T& );
    };
typedef ::boost::variant<test1,test2> var;
var d_;
template< typename U >
    void visit( test1& t, U& u )   //test1 doesn't have set()
    {
    }
template< typename T, typename U >      
    void visit( T& t, U& u )
    {
        t.set(u);
    }
const var& data() const { return d_; }
};
main()
{
    my_type t1, t2;
binary_variant_visitor<my_type> v(t1);
    ::boost::apply_visitor(v, t1.data(), t2.data() );
}
If I change the last line to
  ::boost::apply_visitor(v, t1.d_, t2.d_ );
it works fine on both compilers.
I guess it has something to do with how 
apply_visitor derives the parameter types.
Eugene
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