Explicit.h

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// this is for emacs file handling -*- mode: c++; indent-tabs-mode: nil -*-

// -- BEGIN LICENSE BLOCK ----------------------------------------------
// This file is part of FZIs ic_workspace.
//
// This program is free software licensed under the LGPL
// (GNU LESSER GENERAL PUBLIC LICENSE Version 3).
// You can find a copy of this license in LICENSE folder in the top
// directory of the source code.
//
// © Copyright 2014 FZI Forschungszentrum Informatik, Karlsruhe, Germany
//
// -- END LICENSE BLOCK ------------------------------------------------

//----------------------------------------------------------------------
//----------------------------------------------------------------------
#ifndef ICL_CORE_EXPLICIT_H_INCLUDED
#define ICL_CORE_EXPLICIT_H_INCLUDED

#include <boost/type_traits.hpp>

namespace icl_core {

namespace internal {

template <bool cond> struct ExplicitEnforceMeaning
{ };
template <> struct ExplicitEnforceMeaning<true>
{
  enum { EXPLICIT_TYPE_MEANING_MUST_BE_AN_EMPTY_CLASS_TYPE = 0 };
};

}

template <typename T, typename Meaning>
struct Explicit
{
  Explicit()
  {
    (void) internal::ExplicitEnforceMeaning<boost::is_stateless<Meaning>::value>::EXPLICIT_TYPE_MEANING_MUST_BE_AN_EMPTY_CLASS_TYPE;
  }

  Explicit(T value)
    : value(value)
  { }

  inline operator T () const { return value; }

  T value;
};

}

#endif