On Jul 9, 2008, at 3:02 AM, joaquin@tid.es wrote:
Daryle Walker escribió:
Here's what I'm trying (to redo integer_test.cpp) [...] BOOST_STATIC_ASSERT ( (boost::is_same<distinct_integral_bit_counts, boost::mpl::list_c<int, 8, 16, 32, 64> >) ); }
I think there are two problems with this:
1. You're passing a *type* (boost::is_same<...>) to BOOST_STATIC_ASSERT when you should be passing a numeric contanst. Append ::value to the type.
Can't believe I missed that....
2. Even with the correction above the thing won't work because is_same<T,Q> checks for strict equality of the types T and Q; in your case distinct_integral_bit_counts is *not* the same type as boost::mpl::list_c<...>, but only has the same components. You can use boost::mpl::equal to test this:
BOOST_STATIC_ASSERT ( (boost::mpl::equal<distinct_integral_bit_counts, boost::mpl::list_c<int, 8, 16, 32> >::value) ); }
Other than that, your type_to_digit_count is perfectly lambda- cabable AFAICS. HTH,
Thanks. I switched to mpl::equal and it compiled. I later switched to BOOST_MPL_ASSERT. (Remember to take _out_ the "::value" part!) I originally had the "integral_c" part of "type_to_digit_count" as a member called "type," instead of as a base class, then I switched back and forth. Both ways work. Why is that? And which way is best (if they're not equally good, and without a better third alternative)? //============================== // New type list: integral type -> (wrapped) number of bits // Should the "integral_c" part be a base class or direct member? template < typename T > struct type_to_digit_count //: integral_c<int, std::numeric_limits<T>::digits> { typedef integral_c<int, std::numeric_limits<T>::digits> type; }; typedef boost::mpl::transform<distinct_unsigned_types, type_to_digit_count<boost::mpl::_1> >::type distinct_integral_bit_counts; BOOST_MPL_ASSERT( (boost::mpl::equal<distinct_integral_bit_counts, boost::mpl::list_c<int, 8, 16, 32, 64> >) ); //============================== -- Daryle Walker Mac, Internet, and Video Game Junkie darylew AT hotmail DOT com