[boost] Cast free NULLs in algorithms

31 Jul 2007

      Hello,

I have something like:

class A;
boost::array<A*,10> the_array;

std::fill( the_array.begin(), the_array.end(), NULL );

Which wont compile (at least under Visual Studio 2005) without a cast 
for NULL... I've had this problem before and decided to try to find an 
easy cast free expressive solution for it.

After a few minutes I came up with:

namespace detail
{
     struct null_ptr_impl
     {
         template< typename T >
         operator T* () const { return static_cast<T*>(0); }
     };
} // end namespace detail
const detail::null_ptr_impl null_ptr;

std::fill( the_array.begin(), the_array.end(), null_ptr );

Does this exist somewhere already? Is it a good solution?

Thanks,

Michael Marcin