1
2// Copyright (C) 2009-2012 Lorenzo Caminiti
3// Distributed under the Boost Software License, Version 1.0
4// (see accompanying file LICENSE_1_0.txt or a copy at
5// http://www.boost.org/LICENSE_1_0.txt)
6// Home at http://www.boost.org/libs/local_function
7
8#include <boost/config.hpp>
9#ifdef BOOST_NO_CXX11_VARIADIC_MACROS
10# error "variadic macros required"
11#else
12
13#include <boost/local_function.hpp>
14#include <boost/function.hpp>
15#include <boost/typeof/typeof.hpp>
16#include BOOST_TYPEOF_INCREMENT_REGISTRATION_GROUP()
17#include <boost/detail/lightweight_test.hpp>
18
19BOOST_TYPEOF_REGISTER_TEMPLATE(boost::function, 1)
20
21boost::function<int (int)> derivative(boost::function<int (int)>& f, int dx) {
22 int BOOST_LOCAL_FUNCTION(bind& f, const bind dx, int x) {
23 return (f(x + dx) - f(x)) / dx;
24 } BOOST_LOCAL_FUNCTION_NAME(deriv)
25
26 return deriv;
27}
28
29int main(void) {
30 int BOOST_LOCAL_FUNCTION(int x) {
31 return x + 4;
32 } BOOST_LOCAL_FUNCTION_NAME(add2)
33
34 boost::function<int (int)> a2 = add2; // Reference valid where closure used.
35 boost::function<int (int)> d2 = derivative(f&: a2, dx: 2);
36 BOOST_TEST(d2(6) == 1);
37 return boost::report_errors();
38}
39
40#endif // VARIADIC_MACROS
41
42

source code of boost/libs/local_function/test/return_derivative.cpp