source: downloads/boost_1_34_1/boost/strong_typedef.hpp @ 33

#ifndef BOOST_STRONG_TYPEDEF_HPP
#define BOOST_STRONG_TYPEDEF_HPP

// MS compatible compilers support #pragma once
#if defined(_MSC_VER) && (_MSC_VER >= 1020)
# pragma once
#endif

/////////1/////////2/////////3/////////4/////////5/////////6/////////7/////////8
// strong_typedef.hpp:

// (C) Copyright 2002 Robert Ramey - http://www.rrsd.com . 
// Use, modification and distribution is subject to 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)

//  See http://www.boost.org for updates, documentation, and revision history.

// macro used to implement a strong typedef.  strong typedef
// guarentees that two types are distinguised even though the
// share the same underlying implementation.  typedef does not create
// a new type.  BOOST_STRONG_TYPEDEF(T, D) creates a new type named D
// that operates as a type T.

#include <boost/operators.hpp>

#define BOOST_STRONG_TYPEDEF(T, D)                              \
struct D                                                        \
    : boost::totally_ordered1< D                                \
    , boost::totally_ordered2< D, T                             \
    > >                                                         \
{                                                               \
    T t;                                                        \
    explicit D(const T t_) : t(t_) {};                          \
    D(){};                                                      \
    D(const D & t_) : t(t_.t){}                                 \
    D & operator=(const D & rhs) { t = rhs.t; return *this;}    \
    D & operator=(const T & rhs) { t = rhs; return *this;}      \
    operator const T & () const {return t; }                    \
    operator T & () { return t; }                               \
    bool operator==(const D & rhs) const { return t == rhs.t; } \
    bool operator<(const D & rhs) const { return t < rhs.t; }   \
};

#endif // BOOST_STRONG_TYPEDEF_HPP