#include <iostream>
#include <functional>
 
template<typename T, typename U>
class BinaryFunctor
{
public:
    BinaryFunctor(std::function<U(T,T)> a, std::function<U(T,T)> b): a_(a), b_(b) {}
 
	bool operator()(T left, T right)
	{
		return a_(left, right) < b_(left, right);
	}
 
private:
	std::function<U(T,T)> a_;
	std::function<U(T,T)> b_;
};
 
int plus(int l, int r) { return l + r; }
int minus(int l, int r) { return l - r; }
 
int main(int argc, char* argv[])
{
	BinaryFunctor<int, int> f(plus, minus);
	std::cout << f(1, 2) << std::endl;
 
	std::cin.get();
	return 0;
}

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