Chris@16: // Boost.Units - A C++ library for zero-overhead dimensional analysis and 
Chris@16: // unit/quantity manipulation and conversion
Chris@16: //
Chris@16: // Copyright (C) 2003-2008 Matthias Christian Schabel
Chris@16: // Copyright (C) 2008 Steven Watanabe
Chris@16: //
Chris@16: // Distributed under the Boost Software License, Version 1.0. (See
Chris@16: // accompanying file LICENSE_1_0.txt or copy at
Chris@16: // http://www.boost.org/LICENSE_1_0.txt)
Chris@16: 
Chris@16: #ifndef BOOST_UNITS_STATIC_CONSTANT_HPP
Chris@16: #define BOOST_UNITS_STATIC_CONSTANT_HPP
Chris@16: 
Chris@16: #include <boost/units/config.hpp>
Chris@16: 
Chris@16: /// A convenience macro that allows definition of static
Chris@16: /// constants in headers in an ODR-safe way.
Chris@16: #define BOOST_UNITS_STATIC_CONSTANT(name, type)             \
Chris@16: template<bool b>                                            \
Chris@16: struct name##_instance_t                                    \
Chris@16: {                                                           \
Chris@16:     static const type instance;                             \
Chris@16: };                                                          \
Chris@16:                                                             \
Chris@16: namespace                                                   \
Chris@16: {                                                           \
Chris@16:     static const type& name = name##_instance_t<true>::instance;   \
Chris@16: }                                                           \
Chris@16:                                                             \
Chris@16: template<bool b>                                            \
Chris@16: const type name##_instance_t<b>::instance
Chris@16: 
Chris@16: /// A convenience macro for static constants with auto 
Chris@16: /// type deduction. 
Chris@16: #if BOOST_UNITS_HAS_TYPEOF
Chris@16: 
Chris@16: #if BOOST_UNITS_HAS_BOOST_TYPEOF
Chris@16: 
Chris@16: #define BOOST_UNITS_AUTO_STATIC_CONSTANT(name, value)               \
Chris@16: BOOST_TYPEOF_NESTED_TYPEDEF(name##_nested_t, value)                 \
Chris@16: BOOST_UNITS_STATIC_CONSTANT(name, name##_nested_t::type) = (value)
Chris@16: 
Chris@16: #elif BOOST_UNITS_HAS_MWERKS_TYPEOF
Chris@16: 
Chris@16: #define BOOST_UNITS_AUTO_STATIC_CONSTANT(name, value)               \
Chris@16: BOOST_UNITS_STATIC_CONSTANT(name, __typeof__(value)) = (value)
Chris@16: 
Chris@16: #elif BOOST_UNITS_HAS_GNU_TYPEOF
Chris@16: 
Chris@16: #define BOOST_UNITS_AUTO_STATIC_CONSTANT(name, value)               \
Chris@16: BOOST_UNITS_STATIC_CONSTANT(name, typeof(value)) = (value)
Chris@16: 
Chris@16: #endif // BOOST_UNITS_HAS_BOOST_TYPEOF
Chris@16: 
Chris@16: #endif // BOOST_UNITS_HAS_TYPEOF
Chris@16: 
Chris@16: #endif // BOOST_UNITS_STATIC_CONSTANT_HPP