local_function/test/addable.hpp

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// Copyright (C) 2009-2012 Lorenzo Caminiti
// Distributed under the Boost Software License, Version 1.0
// (see accompanying file LICENSE_1_0.txt or a copy at
// http://www.boost.org/LICENSE_1_0.txt)
// Home at http://www.boost.org/libs/local_function
#ifndef ADDABLE_HPP_
#define ADDABLE_HPP_
#include <boost/concept_check.hpp>
template<typename T>
struct Addable { // User-defined concept.
BOOST_CONCEPT_USAGE(Addable) {
return_type(x + y); // Check addition `T operator+(T x, T y)`.
}
private:
void return_type(T) {} // Implementation (required for some linkers).
static T const& x;
static T const& y;
};
#endif // #include guard