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