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// Boost.Signals library
// Copyright Douglas Gregor 2001-2003. 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)
// For more information, see http://www.boost.org
#include <boost/signals/signal2.hpp>
#include <iostream>
template<typename T>
struct first_positive {
typedef T result_type;
template<typename InputIterator>
T operator()(InputIterator first, InputIterator last) const
{
while (first != last && !(*first > 0)) { ++first; }
return (first == last) ? 0
: *first;
}
};
template<typename T>
struct noisy_divide {
typedef T result_type;
T operator()(const T& x, const T& y) const
{
std::cout << "Dividing " << x << " and " << y << std::endl;
return x/y;
}
};
int main()
{
boost::signal2<int, int, int, first_positive<int> > sig_positive;
sig_positive.connect(std::plus<int>());
sig_positive.connect(std::multiplies<int>());
sig_positive.connect(std::minus<int>());
sig_positive.connect(noisy_divide<int>());
assert(sig_positive(3, -5) == 8); // returns 8, but prints nothing
return 0;
}
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