Here's a bit of code (and my apologies for it's length, but I'm unsure
which bit is the failure point)
#include <cstddef>
#include "boost/lambda/lambda.hpp"
#include "boost/lambda/bind.hpp"
#include "boost/function.hpp"
#include "boost/type_traits.hpp"
namespace
{
template < bool >
struct cmp_detail
{
template < typename T >
static bool cmp( const T & lhs, const T & rhs )
{
return lhs != rhs;
}
};
template < >
struct cmp_detail< true >
{
template < typename T, std :: size_t sz >
static bool cmp( const T ( & lhs )[ sz ], const T ( & rhs )[ sz ] )
{
using boost :: lambda :: _1;
using boost :: lambda :: bind;
using boost :: lambda :: var;
boost :: function< bool( unsigned ) > cmp_element =
bind( cmp_detail< boost :: is_array< T > :: value > :: cmp,
var( lhs )[ _1 ], var( rhs )[ _1 ] );
for ( unsigned i = 0; i != sz; ++ i )
if ( cmp_element( i ) )
// if ( cmp_detail< boost :: is_array< T > :: value > :: cmp( lhs[ i ], rhs[ i ] ) )
return true;
return false;
}
};
template < typename T >
bool cmp( const T & lhs, const T & rhs )
{
return cmp_detail< boost :: is_array< T > :: value > :: cmp( lhs, rhs );
}
template < typename T, std :: size_t sz >
struct Block
{
typedef T type[ sz ][ sz ];
};
}
int main( )
{
Block< int, 16 > :: type a;
Block< int, 16 > :: type b;
cmp( a, b );
}
The problem is the bind call in cmp_detail<true>::cmp(...). Error is this
block.cpp: In static member function `static bool <unnamed>::cmp_detail< true>::cmp(const T (&)[sz], const T (&)[sz]) [w
ith T = int[16], unsigned int sz = 16u]':
block.cpp:45: instantiated from `bool <unnamed>::cmp(const T&, const T&) [with T = int[16][16]]'
block.cpp:61: instantiated from here
block.cpp:32: error: no matching function for call to `bind(<unknown type>, const boost::lambda::lambda_functor<boost::l
ambda::lambda_functor_base<boost::lambda::other_action<boost::lambda::subscript_action>, boost::tuples::tuple<boost::lam
bda::lambda_functor<boost::lambda::identity<const int (&)[16][16]> >, boost::lambda::lambda_functor<boost::lambda::place
holder<1> >, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boo
st::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type> > >, const boost::l
ambda::lambda_functor<boost::lambda::lambda_functor_base<boost::lambda::other_action<boost::lambda::subscript_action>, b
oost::tuples::tuple<boost::lambda::lambda_functor<boost::lambda::identity<const int (&)[16][16]> >, boost::lambda::lambd
a_functor<boost::lambda::placeholder<1> >, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type,
boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::
null_type> > >)'
I think perhaps the var() calls are not preserving constness quite right? Any help would be welcome.
Thanks.
- Rob.