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_LAMBDAS
10# error "lambda functions required"
11#else
12
13#include <iostream>
14#include <cassert>
15
16//[expensive_copy_cxx11_lambda
17struct n {
18 int i;
19 n(int _i): i(_i) {}
20 n(n const& x): i(x.i) { // Some time consuming copy operation.
21 for (unsigned i = 0; i < 10000; ++i) std::cout << '.';
22 }
23};
24
25
26int main(void) {
27 n x(-1);
28
29 auto f = [x]() { // Problem: Expensive copy, but if bind
30 assert(x.i == -1); // by `&x` then `x` is not constant.
31 };
32 f();
33
34 return 0;
35}
36//]
37
38#endif // NO_LAMBDAS
39
40

source code of boost/libs/local_function/example/expensive_copy_cxx11_lambda.cpp