template<typename T> struct print_log_value { void operator()( std::ostream& ostr, T const& t ) { #if !BOOST_WORKAROUND(BOOST_MSVC,BOOST_TESTED_AT(1310)) // Show all possibly significant digits (for example, 17 for 64-bit double). if( std::numeric_limits<T>::is_specialized && std::numeric_limits<T>::radix == 2 ) ostr.precision(2 + std::numeric_limits<T>::digits * 301/1000); #endif ostr << t; // by default print the value } };
Would solution like following will cover all FPTs? template<typename is_spec> struct set_log_precision { static _( std::ostream& ostr ) {} } // Show all possibly significant digits (for example, 17 for 64-bit double). template<> struct set_log_precision<true> { static _( std::ostream& ostr ) { ostr.precision(2 + std::numeric_limits<T>::digits * 301/1000); } } template<typename T> struct print_log_value { void operator()( std::ostream& ostr, T const& t ) { set_log_precision<std::numeric_limits<T>::is_specialized && std::numeric_limits<T>::radix == 2>::_( ostr ); ostr << t; } }; Gennadiy